Saturday, October 2, 2010

Wart Zapper Project

A Recent History
By now, the Wart Zapper has quite a history behind it. Three different embodiments have been published in three major magazines. It has gone into production in South Africa, and (without my having read the technical details) an embodiment would seem to have gone into production in the USA. In the latter case, it has been advertised also as a cure for cold sores. A major company approached me with a view to manufacture. However, the medical trials and approvals seemed to be too much of a hurdle for me to want to further pursue that avenue.
The Wart Zapper's record has been good. I have received many letters confirming its efficacy -- not to speak of the results that I have witnessed first hand. One writer had a problem getting his unit to work, and I "walked him through" the problems. He replied: "I did another set of 'zaps', and wow!! As per the article, about 3 minutes in, a small wart on my thumb suddenly got quite sore (which I bore with dignity). Et voila!! After about 5 minutes there was a tiny hole burnt in it. This has now formed a hard layer, and I am confident its wave function has collapsed."

A few people had some difficulty obtaining a result at first. This was always where a wart was both large and "dry". In one or two cases, the problem was solved by soaking the wart in the bath, then applying the Wart Zapper. This is also covered below.

Wart Removal

As improbable as it may seem, the common wart may be destroyed with a simple circuit that uses a small 9V PP3 battery delivering a boosted 25V to the skin. Taking into account the resistance of the skin, this translates to just 100µA or so passing through the wart internally, thus delivering a fraction (about one-third) of the peak power delivered by a typical TENS unit. That is, a typical wart may be destroyed with the power that a pocket torch uses in the blink of an eye.

Warts are one of the most common maladies of humankind, yet are often one of the most awkward to cure. In the past, warts were removed by means of curettage (that is, cutting them out), or by burning them off -- sometimes with a hot coal. Often they were simply left alone. One of the more famous quotes of Oliver Cromwell, Lord Protector of England, was, "Paint me warts and all, or not at all!" Due to the habit of warts of suddenly and inexplicably disappearing, it was sometimes thought that charms might effect the cure.

Today, there are three lines of attack to remove warts:

Perhaps the most common is the dreaded liquid nitrogen treatment (also called cryosurgery). However, not only is this messy and painful -- it may in many cases augment the treated warts, or do permanent damage to the skin -- particularly to darker skin.

Chemical treatment is often a long, slow, messy process which requires perseverence and care -- and even then, success is not guaranteed. This may also be couter-productive, and generally cannot be used on the face.

A third method, which is often used in clinics today, is electrodesiccation (or sometimes, "radio frequency thermal ablation") -- that is, burning off warts electrically with several Watts of power. This is tidy, quick, and effective, yet it tends to be expensive, and requires specialist attention. Therefore it is likely to lie beyond the means of people who live in poorer circumstances, or in more remote areas of the world.

What is significantly new about the circuit shown here is that it brings wart removal within the scope of every amateur electronics constructor, using some one thousand times less power than electrodesiccation. For the price of a doctor's consultation for the dreaded liquid nitrogen treatment, or for the price of a single session of electrodesiccation, several Wart Zappers could be built.

The single 9V PP3 battery used by this circuit should be capable of destroying a many warts. In trials, the Wart Zapper proved to be close to 100% effective for the so-called common wart, on condition that this was not too large (that is, if it was less than 5mm across it at its widest point). In particular, the Wart Zapper was very effctive with warts on the hands, which are often the most difficult to remove by other methods. Larger warts may by all means be treated, but these may prove to be more awkward to remove.

Medical History

During the 1950's, Dr. John Crane experimented with the treatment of harmful microbes with electrical pulses. This followed experiments in the 1930's by Dr. Royal Raymond Rife, who used electromagnetic pulses, which yielded some remarkable results. Dr. Rife's original interest was in the design of microscopes, and his discovery of the effects of electromagnetic radiation on microbes came purely by accident as he sought to illuminate specimens under his ever more powerful microscopes.

In short, Dr. Crane claimed to have established that harmful microbes, if pulsed with a small current at a specific frequency, will resonate, thus destroying the microbes, while leaving healthy tissues intact.

Since warts are known to be caused by a group of common viruses, the present design uses a frequency close to one established by Dr. Crane for the treatment of the "wart virus" (21.27kHz). This is used here with suitable voltage and current. It has since been questioned whether Dr. Crane's frequencies are at all significant, or whether any frequencies within a few hundred or even thousand Hertz would work just as well. However, Dr. Crane's original frequency it is, with the important difference that it is applied here directly to a wart, rather than being used as a treatment for the virus.

It is interesting to note that Dr. Crane's frequencies for cancer (sarcoma and carcinoma) lie close to those for the wart virus. This raises the possibility that the Wart Zapper might work for certain cancers. In fact it was tested on a less aggressive form of skin cancer under the eye of a specialist, and it successfully destroyed the cancer. However, the Wart Zapper would not be recommended in such cases, since one cannot afford to take chances with personal experiments on cancers.

The Wart Zapper originally came about by accident. I was experimenting with Crane frequencies to treat a superficial infection that had eluded antibiotics. With a lot of guesswork as to what voltage or current to apply, the treatment was surprisingly and entirely successful -- yet caused a little damage to the skin. What if, I thought, Dr. Crane's frequencies would cause similar damage to warts?

My first prototype yielded patchy results, but these were sufficiently hopeful to know that they were significant. Four successive prototypes were tested on several volunteers, including medical professionals, with the final prototype achieving close to 100% success with the common wart (a brown or skin-coloured, rough wart), as well as some success with other types of wart, such as the plane wart. The Wart Zapper's high success rate does not of course guarantee that it will work in every case. However, it does offer reason for hope that the device would be effective in a great many cases.

Note that, although the Wart Zapper was developed on the theories of Dr. John Crane, and although I have my own "best guess theory" as to why it works, at least five different theories have been put forward as to why it works -- see the sidebar.

Safety and Caution

Despite the very small currents used by this circuit, little is understood about the effects of electricity on the human body, and the Wart Zapper should be used with this caution in mind.

During experiments, I was surprised by the profound effect that miniscule currents may have on the human body. When I was still seeking to establish the correct "exposure" required to destroy a wart, I caused significant damage to a fingernail 7 cm (nearly 3") distant. Similarly, related devices which are used to treat viral infections have been said on occasion to cause e.g. stiffness in a finger joint.

These are rare and relatively minor side-effects, yet it should be borne in mind that the Wart Zapper is capable of doing some damage if misused. Therefore the voltage, current, frequency, and duration of treatment described in this article should not be rashly modified. More than a year's experimentation, and even more "field experience", lies behind this design, and most if not all of the mistakes have hopefully been made.

The Circuit

The Wart Zapper uses a single CMOS 7555 oscillator (IC1), for dual purposes, as follows:

First, it pumps up a standard voltage tripler circuit, represented by the capacitor-diode network to the right of IC1 in the circuit diagram. This takes the voltage up to about 25V, if not a little more. The purpose of increasing the voltage is to overcome the resistance of the skin. According to the well known formula I=V/R, if V (voltage) is increased, while R (resistance -- in this case skin resistance) remains the same, I (current) increases proportionately.

Second, the oscillator switches power MOSFET TR1 at the required frequency, to pulse the raised voltage through the skin by means of two electrodes. One of these electrodes is positive (+25V -- called the dispersive electrode, and marked D. This may either be a metal grip held in the hand, or a metal plate applied to a large(ish) area of skin near a wart. The other electrode is negative (0V -- called the active electrode, and marked A). This is a sharp(ish) metal point which is used for direct contact with the wart. The 470k potentiometer VR1 is inserted into the dispersive electrode's lead to prevent the possibility of a brief electrical jolt at switch-on, or on first applying the active electrode to a wart.

After much experimentation, I settled on a 25V 21kHz square wave (the circuit will approach this to within about 10%), applied to a wart for five minutes. I found that pulses of a minimum 1mW power passing through the wart internally were required to achieve any effect, and that 3mW-6mW pulses were adequate (compare this with the approximately 2W required to illuminate a pocket torch)!

Current across the probes is limited by R3 to less than 3mA, to protect the circuit if these should be short-circuited. One needs also to factor in the conductivity of the flesh, which rarely falls below about 200k -- therefore little more than 100µA, or at most about 200µA, would course through the wart itself.

Zener diode ZD1, together with LED D1 and resistor R1, serve as a simple "battery low" indicator. LED D1 will normally glow dimly, and this must be a green LED -- it is chosen for its so-called forward voltage drop, which differs from that of other coloured LEDs. If this LED goes out, then the battery is flat, and needs to be replaced. C1 serves as a supply decoupling capacitor, and S1 as an on-off switch.


Construction
The Wart Zapper (see Fig.2) is built on a printed circuit board (PCB) measuring approximately 60mm x 44mm (2.5" x 1.8"). The prototype used a case measuring approximately 100mm x 60mm x 22mm (4" x 2.5" x 1") externally.

Begin by soldering the six solder pins to the PCB. Solder the four resistors, the six capacitors (observing the polarity of electrolytic C1), the Zener diode, the five remaining diodes (including LED D1), and power MOSFET TR1. Then solder the battery leads as shown. The positive lead is taken via switch S1. Be sure to connect the leads the right way round, since a mistake here could destroy the circuit.


















Fix the PCB to the bottom of the case, perhaps with some epoxy glue. A hole is prepared in the case for LED D1, which may be wired directly to the PCB, depending on the layout of the case. The cathode (k) of D1 is identified with a "flat" on the side of its encapsulation. Mount on-off switch S1 on the case.
 Attach a long, plastic sheathed wire to the dispersive electrode (a metal grip or metal plate), and pass this wire through a hole in the case. Make sure that there is sound electrical contact between the wire and the metal grip or plate. Take the free end of this wire to 470k potentiometer VR1, and wire the potentiometer to the PCB as shown. If the potentiometer is viewed from underneath with the terminal pins facing towards you, the two terminal pins on the right need to be wired to each other.


Then attach a long, plastic insulated wire to the active electrode (a sharp pin -- but not too sharp -- the end may be filed flat), and pass this wire through a hole in the case, soldering it also to the PCB as shown. The pin should be inserted in a suitable plastic shaft so that it is not directly touched when treating a wart. Finally, insert and solder IC1 on the PCB, observing anti-static precautions (touch your body to ground before handling, e.g. to a metal tap).
In Use
Removing warts has never been much fun, and the use of the Wart Zapper is likely to be painful -- but only briefly, and not too much (as hinted at in the constructor's letter above).
Considerable experimentation preceded the development of this circuit, and, as mentioned, the results gave me a new respect for the potential risks of electricity, however small the voltages and currents that are applied. Skin resistance can vary between about 100k and 10M, depending on the day and the situation. Therefore, to ensure consistency of results, skin resistance needs to be kept relatively low. Use a little skin moisturiser where the skin makes contact with the dispersive electrode, as well as a little moisturiser on the wart itself.
Constructors are advised not to use the circuit where current would flow across the head or the heart, and never during pregnancy, or where a person uses a pacemaker, or has any history of epilepsy. These are standard safety recommendations for TENS devices, which incidentally use some three times the peak power of the Wart Zapper.
If treating a wart e.g. on the lower or upper arm, hold a metal grip (the dispersive electrode) in the same hand. If it is not convenient to use a grip, rest the limb to be treated (e.g. a foot) on a metal plate instead, which is again connected as the dispersive electrode. The active electrode -- that is, the sharp(ish) metal point -- is rested directly and gently on the top of the wart. If treating a slightly larger wart (say more than 4mm at its widest point), it might be an idea to tackle one or the other side of it first, since the Wart Zapper is unlikely to kill it all at once.
Switch on, apply the Wart Zapper to a wart for up to five minutes (see above), then switch off. Potentiometer VR1 is used to turn up the power slowly to full after switching on -- however, for the brave, it may be turned up full immediately. Be prepared suddenly to experience perhaps half a minute of sharp pain. If you do not see this through until the pain subsides (which it will), the wart may not be destroyed.
Experience and Qualifications
Although most common warts were ultimately removed by the Wart Zapper, it was found that there were some differences in the effect that the device had.
In several cases, a wart was obliterated first time, never to return. These were usually small common warts about 2mm to 4mm at their widest point. However, with close constellations of warts (at first glance looking like a single wart), or with larger warts, the wart was sometimes destroyed in part, but needed follow-up treatments to destroy it all.
In most cases, little or no pain was experienced when the Wart Zapper was first applied, although one subject jumped when the device was first switched on, and another -- a dentist -- suggested a means of controlling the power at switch-on. This is taken care of in the present design with a potentiometer which the patient may slowly turn up once the so-called active electrode is resting on the wart. In most cases, however, this potentiometer would not be missed.
After a certain period of painlessness, which varied from about half a minute to three-and-a-half minutes, subjects suddenly felt a burning or even a "spine-chilling" pain, inside and under the wart. This pain only lasts about half a minute, then subsides. However, it is necessary for the removal of the wart, and needs to be "stuck out". When the pain has subsided (or after five minutes, whichever may come first), the probe is removed.
Be more careful with facial warts, since facial skin is delicate. Rather under-treat such a wart than over-treat it. You may always return to it again later.
Once a wart has been treated, it should immediately be apparent that it is "just not the same". In fact in many cases, the wart melted with a fizzle even before the treatment was over. The skin immediately surrounding the wart may be irritated for a few hours, and there may be a slight swelling close to the wart. Ultimately a scab may form. Don't ever remove a wart too soon, or break its surface, or even agitate it, since this could leave a deep wound, and there could be infection. If it is left alone, there should be no infection. If a treatment should have little or no effect, it would be sensible to consult a doctor.
While this circuit comes with no guarantees, it is no doubt a case nothing ventured, nothing gained! With the help of several willing "guinea-pigs", and further volunteers queuing up, I found that the Wart Zapper was entirely successful most of the time.



Alternate PCB View
Theory and Practise

According to the original theory of Dr. John Crane, alien cells (such as viruses) begin to resonate when bombarded with a specific electrical frequency. Normal chemical processes at the cell boundary are thereby disrupted, or the cell ruptures, thus killing the cell. Healthy tissues are left almost entirely unscathed.
However, this is not the only theory in the running. By way of a process of elimination, I followed up further suggestions put to me by researcher Aubrey Scoon:
1. Electrolysis (a "flat" DC voltage). This also did significant damage to warts - however, it also did immediate, superficial damage to healthy tissues, and the experiment was not repeated. The conclusion is that electrolysis may contribute to the destruction of warts, but it does not offer an adequate explanation for the Wart Remover's success.
2. Iontophoresis. This is the leaching of ions into a wart, which effectively kills the wart by poisoning. However, after experimenting with a variety of conductive electrodes, as well as graphite (all the electrodes were tried with success), this theory was safely ruled out.
3. The stimulation of immunomodulatory chemicals. The theory is that these chemicals, when stimulated by an electrical frequency, attack the wart and destroy it. However, this would be hard to explain in light of the spectacular destruction of some warts. In some cases, the Wart Eliminator appeared to explode wart cells, and this could on occasion even be heard! Finally,
4. Frictional heating. Ionic agitation may raise the temperature within a wart, causing tissue coagulation. While I had no way of testing this theory, I thought it unlikely. Electrodesiccation typically raises the temperature within a wart above 47°C, and this requires a few Watts of power. Since the Wart Remover pulses just one-thousandth as much power through a wart, this possibility would seem less probable.

Parts List
Qty Part
1 Copper clad board 60mm x 44mm (2.5" x 1.8")
1 9V PP3 "matchbox" battery
1 Battery clip for battery - or suitable case with internal battery terminals
1 Panel mounting on-off switch
1 Suitable ABS plastic case approx. 100mm x 60mm x 22mm (4" x 2.5" x 1") external
1 1 metre (1 yard) plastic shielded wire for the electrodes
1 15 cm (6") long brass tube for the dispersive electrode
1 Needle sharp tip filed off - for the active electrode
1 8-pin dual-in-line (DIL) socket (not required for experienced constructors)
6 Solder pins
1 Etchant if a PCB needs to be etched
1 Solder

Semiconductors
1 6.8V Zener diode (¼-Watt is adequate)
1 Green LED (no other colour)
4 1N4148 signal diodes
1 IRF610 power "logic" MOSFET (alternatively IRF510, BUZ11, BUZ22)
1 7555 CMOS timer IC

Resistors
2 1k ¼-Watt carbon or metal film
1 47k ¼-Watt carbon or metal film
1 10k ¼-Watt crbon or metal film
1 470k or 500k potentiometer, carbon track or conductive plastic
1 Knob for potentiometer

Capacitors
1 680pF polyester or ceramic
2 100nF polyester or ceramic
2 220nF polyester or ceramic
1 100µF electrolytic 16V or higher

author: Thomas Scarborough
e-mail:
web site: http://www.zen22142.zen.co.uk

Dot matrix LED running display with improved characterstics


Features
LED dot matrix display 40x7;
- Display of clock, calendar, inside and outside temperature, text messages;
- Automatic Daylight Savings Time;
- Capability of keeping the real time clock working correctly for more than one week
without power supply;
- Inside temperature measurement (0 ÷ +75) °C, ±0.5 °C accuracy;
- Outside temperature measurement (-40 ÷ +75) °C, ±0.5 °C accuracy;
- Supports static and running messages with different effects;
- Full Cyrillic and special symbols supports;
- Memory for 10 messages, each including up to 250 symbols;
- Automatic brightness control;
- IR remote control for settings messages select;
- Power supply: 12 ÷ 24V DC;
- Front panel dimensions 305 x 69 mm.

Schematic description


 The device comprises two parts: LED control board and LED display board. The two PCBs are designed to fit together one behind the other using two sets of dual row connectors and 4 spacers. One of this connector is used for the electrical connections, while the other is only used as a mechanical connecting element.
The core of the device is microcontroller PIC18F252 (U9). It controls all the functions of the device, generates the overall algorithm to control the LED matrix. LEDs are connected in matrix 40x7. The columns tie together the cathodes of the LEDs and rows tie the LEDs anodes. The LED matrix is controlled dynamically in row by row. To safe space and number of components, the LEDs are driven with specialized LED driver STP16CP05 (U101-U103), produced by ST Microelectronics.


Each of these IC contain 16-bit serial-in, parallel-out shift register, latch register and 16 constant current output channels. Outputs are open drain type, allowing connection of a load supplied with up to 20V supply voltage. The constant current for all outputs varies from 5 to 100 mA and is set from an external resistor (R115-R117). In this application, the three LED drivers are connected in a cascade and controlled from the microcontroller over SPI protocol. The microcontroller sends a 48-bit word, controlling one row at the time. The 40 LSB represent LED states (1-On, 0-Off) in the row and control their cathodes. The 7 MSB control the anodes through the 7 driver transistors (VT101 - VT107). The 40th bit remains unused. The microcontroller sends the 48-bit word every 1 ms.
There are 7 cycles to display each row plus an extra blank cycle, used to process temperature measurements. Thus, the refresh rate of the display is 125Hz. To control the display brightness is used the "outputs enable" (OE) pin. Each row cycle begins with logical 0 on the OE pin (outputs are enabled). The duration of an enabled signal changes depending on the desired brightness, using the microcontroller's on-chip PWM module.
You should note that numbers of columns and rows are not sequential to the corresponding pins of the ICs (U101-U103). This aims to simplify the design of PCB. The LEDs' corresponding bits are rearranged by software to fit with their physical order.

Real-time clock / calendar
The real time clock is implemented with U10 - PCF8583. This is a clock / calendar / alarm circuit with I2C interface and on-chip 32768Hz oscillator. The PCF8583 contains all necessary counter registers to provide real time clock and date information. Its power consumption is very low (typical supply current is 10 A). It operates in wide range of supply voltage from 1 to 6V. These features will make it possible to have a real time clock available for a long time using a small lithium battery or even a back-up capacitor. The designed PCB provides both options.
The footprint for lithium battery is suited for 2032 type socket. The experiments using 1F backup capacitor show that the clock remains active more than a week after turning-off the power supply. The diodes VD10, VD11 and VD12 should be Shotkey type as shown in the scheme because of their low drop forward voltage. Trimmer-capacitor C21 is used to adjust the oscillator frequency at 32768Hz. For I2C communication is used the Master Synchronous Serial Port (MSSP) module in PIC18F252. This module is set in I2C master mode. On the same bus an external EEPROM (U11) can be connected to expand the capacity of the data storage. The present version of firmware does not need an external EEPROM, so it can be omitted.



 Temperature measurement
For ambient temperature measurement are used LM35 sensors (U5, U6). They are factory calibrated directly in ° Celsius. The output response is 10mV/°C. The supply voltage should be between 4 and 30 Volts. To make a full-range temperature measurement, a negative voltage must be applied to the output through a resistor (R4 and R5). To ensure this requirement, the ground pins of the sensors are connected to the analog ground through two diodes (VD4,VD5 and VD6,VD7), which pick them up with approximately 1,4V.
In that case the Vcc (+5V) power supply is not enough for LM35, so additional voltage regulator U1 (78L09) is needed to be used. The signal from the sensor is taken between the output and the negative pins of the LM35. The voltage between these two pins is bipolar with polarity depending on the measured the temperature sign. The sensors could be connected with external three-wire cables. Software is designed to show inside temperature from U6 and outside temperature from U5.


 
A/D converter
Both LM35's outputs are connected to U4 - MCP3302. This is a Successive Approximation Register (SAR) analog to digital converter. It provides 13 bits resolution (12 bits plus one sign bit). The MCP3302 has 4 analog inputs, which can be configured either as 4 single ended or as 2 differential inputs. The application requires 2 differential inputs to convert both bipolar voltages from the LM35 temperature sensors. As a reference voltage is used U7 - LM336-2,5.

Its output value needs to be adjusted at 2,55V using a trimmer-potentiometer RP1. VD8 and VD9 are used for temperature compensation. The MCP3302 has an SPI interface, using four signal lines. These lines are under software control from the microcontroller (U9). To ensure accuracy the analog ground is separated from the digital using small ferrite beam (L6). This is an SMD type Z600 ferrite beam in 0805 package. The same type is used to decouple the power supply for A/D converter and for temperature sensors and reference voltage (L4 and L5 respectively).

Brightness control
For an automatic brightness control is used a light-to-voltage converter - U8 (TSL257). Its output voltage is directly proportional to the light intensity on the built in photodiode. The voltage from the light sensor is measured using an on-chip microcontroller ADC. The ADC value affects the PWM module from where the LED panel changes its brightness. To avoid unwanted blinks of the display, a slight software delay of the PWM control is applied.


 
Display functions
The display settings are adjusted from the user with three local buttons S1-S3. The meaning of these buttons is as follows: S1 - UP; S2 - DOWN; S3 - SET.
 

Clock settings
To enter in settings mode press once SET button. A "Settings" label appeared on display. To set the clock and date, press UP or DOWN buttons to select "Set time". Press the SET button again and display will show the current time, where the hours' digits are blinking. Use UP/DOWN buttons to adjust the correct hours. Then press SET to select minutes. After the minutes are set, the display will switch to date adjustment. Adjust date, month and year and press SET to finish. The software automatically calculates the day of the week.
If an incorrect date is selected (for example 29.02.10), the display will show an "ERROR" message for a while and will return at the beginning of the date adjustment. When the date is set correctly the display will show a new set clock with blinking "OK" and will wait to confirm the new clock/date values. If the UP button is pressed again the display will ignore the new values and returns at "Settings" mode. If the DOWN button is pressed the display will return at the first step of the "Set time" procedure. When the button SET is pressed a new clock and date value are accepted, seconds are reset and display will run in normal mode. The software automatically switches on Daylight Savings Time (+1 hour). It happens on the last Sunday in March, at 3:00 o'clock a.m. Return to winter-time (-1 hour) is done on the last Sunday in October, at 4:00 o'clock a.m.


 
Brightness settings
The user can select the brightness level in 8 steps or select an auto mode. To change the brightness from "Settings" menu, select Bright and press SET. The display will show the current bright level (from "Bright 1" to "Bright 8") or "Bright A" for auto mode. The desired value is selected by pressing the buttons UP and DOWN. When the SET button is pressed again, the selected value will accept and store it in EEPROM. To exit from "Settings" menu and return in normal mode of display press SET button, when a label "Settings" appears.  

IR remote control
An additional feature of the device is the possibility to change settings using an Infrared remote control. It allows the device to be installed on a place with difficult access. The decoder is implemented with microcontroller PIC12F675 (U52) and designed to work with a standard TV remote control, matching RC5 protocol. This protocol is supported from TV Philips.
The decoder received a demodulated digital signal from IR receiver TSOP1736. The software decodes the received command and transmits it to the main microcontroller U9 over an asynchronous serial connection. The LED VD51 blinks once at each recognized command. The main microcontroller (PIC18F252) receives commands from IR decoder using its hardware Universal Synchronous Asynchronous Receiver Transmitter (USART) module. Because the same module is also used for a RS232 connection to the PC, the RX signal is multiplexed between the U52 output or U71 (MAX232) output. Switch is implemented by the 4 NAND elements in U53 (74HC00). Unfortunately, the present version of the firmware is not ready to control a RS232 communication. So for that moment U71, U53, J71 and their adjacent elements can be omitted.

The available buttons from TV remote control are as follows:

- PROGRAM UP - equivalent to local button S1 - UP;
- PROGRAM DOWN - equivalent to local button S2 - DOWN;
- MUTE - equivalent to local button S3 - SET;
- MENU - equivalent to local button S3 - SET (not working with all remote controls);
- Direct buttons from 0� selects predefined messages. From messages 1 to 4 display will show static message of clock, date, outside and inside temperature, respectively. From 5 to 9 and 0 the display shows all available data with different effects.

 Power supply
 The device needs three different stabilized supply voltages: Vcc (+5V) for main part of scheme, Vled (+2,5V) for LEDs' anodes and a +9V for temperature sensors. For high-efficiancy Vcc (+5V) and Vled (+2,5V) are provided using a step-down regulator. For a +5V is used U2 (LM2575-5.0) and for Vled is used U3(LM2576-ADJ). Because the consumption from the +9V is very low, it is implemented with low power version of standard linear regulator 78L09. Vth1, VD14 and R18 realized overvoltage protection. If the voltage of Vcc exceeds the zener diode voltage plus thyristor gate voltage the thyristor starts to open and gives short circuit Vcc to ground. This protects all the integrated circuits from accidentally raising the supply voltage.
The external power supply must have a fuse or current limiter. Of course, this protection circuit is not necessary, but strongly recommended, especially at the stage of testing. Other two power supplies are not so critical if the voltage is increased. The LED drivers' outputs can work with
up to 20V load and limits the current through the LEDs. The ICs LM35 and LM336 can also work with higher than 9V power supply. It is necessary to pay attention to the Vled voltage. Its value is very important due to the power dissipation in the LED drivers. In this case are used super bright red LEDs dot matrix modules 5x7 (TC20-11SRWA). The LED forward voltage Vf is 1,85V at 20mA. It won't be a problem
to use other type of LEDs. For reliable work the Vled should be 0,5-0,7 higher than the Vf. But not more higher, because the power dissipation in the drivers will increase and the thermal shut-down protection will be activated. To calculate the Vled is used the next formula:

where R2 is between 1 and 5 kOhm. It is also needed to choose a proper value for LEDs current. The current is set with R115, R116 and R117 resistors, connected to pin 23 (R EXT) of LED driver. The showed value (270Ohm) sets a current of approximately 80mA per output. Because the duty cycle of each row is 1/8, the average current through the LED is 10mA. See the STP16CP05 datasheet for output current resistor set. For convenience of changing these resistors, the footprints of R115 and R116 are duplicated next to R117, named R115' and R116'.

In conclusion
Any special adjustments are required to start the device. If it is assembled properly and two microcontrollers are programmed it will immediately start running. U9 can be programmed with one of the two available connectors J4 or J4A depending on the programmer type. It is possible to need to disconnect the Vcc from U9 during programming. For that purpose JP1 is provided. The U52 must be programmed externally.
Please note, that the two double row connectors connecting the two boards are SMD type. The clearance between the pins is 2,00mm, not 2,54!

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I am an electrical and electronics engineering kathmandu university batch 2007
 
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