Top Circuits Page 251
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Describes reading a thermistor using an Atmel ATtiny45 or ATMega168 microcontroller to drive two fans to cool a PC installed in a kitchen cabinet. Include a table for converting the BC1482 resistance to Fahrenheit....
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The Flip-Flop Robot drives forward until it hits an obstacle, and then reverses until it hits another obstacle. This back-and-forth process continues indefinitely. By limiting the functionality to this very rudimentary behavior, it can be generated from an....
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The simplest solution for implementing joystick control for a robot would be to program the actions in software in a microcontroller. But, since many readers prefer off-the-shelf parts, this circuit is going to be made with diodes, resistors, transistors,....
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Most of my circuits still use 5 V regulated power for the chips, because 8-bit microcontrollers run faster and some sensors require 5 V. Since 5 V is more than enough for even a white LED, I`m not concerned with the voltage needed by a particular LED in use.....
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The laser-pointer detection circuitry is able to determine when a laser light is aimed at a particular photosensor. If the laser is aimed at the top sensor, the comparator chip outputs on . If the laser is aimed at the bottom sensor, the comparator chip....
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To understand how the 74AC14 PWM circuit works, let`s zoom in on the section of the schematic containing the trimpot, diodes, capacitor, and the first inverter logic gate. The capacitor is empty (discharged) when the power is first applied to the circuit.....
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Discrete blinking LEDs are convenient, but the blink rate and blink duration are not configurable. I tried goofing around with using transistors, resistors, and capacitors to alter the blinking LED. In the end, I had so many extra electronic components that....
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One of the first lessons that an electronics student learns is that an LED provides light from current flow. But, did you know that an LED put in backwards provides current flow from light Yes! It`s true. Hook up a high-quality ultra-bright red LED by itself....
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This circuit adds a datasheet-compliant trigger signal, reversed polarity protection, optional test button, and optional battery operation. U1 L601E3 or MAC97A8 triac. 400 V, 1 A. When U1 is enabled, the + and - wires of the flash are electrically connected,....
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To obtain the power supply graphs on the previous page, I didn`t stand outside for two days straight measuring the power sources with a voltmeter. Instead, the circuit itself is able to independently monitor the power sources with the addition of a few....
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Need more current If you`ve got a larger motor waiting to be used, the Pololu High Current Motor Driver Board 14A 6V-16V is just what you need. Connect three digital lines to your microcontroller (five if you want error condition feedback), and you`re ready....
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This is a very crude handdrawn schematic version 2. I`ll pop it into Protel later when I get the time. But it does give you a very handy overview of the circuit where it`s possible to charge from 2 different sources. Either by USB or normal charger. Also....
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Figure shows a simplified representation of the Earth`s dipole field, it resembles the field due to a bar magnet. The field lines originate at the south magnetic pole and terminate at the north magnetic pole. The angle that this field makes when it....
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This is a very simple circuit where the PIC and an internal 1kHz sinewave table do all the hard work of making an accurate sinewave. Then it needs only a few external parts for filtering. The sinewave has a very high frequency accuracy as it is generated....
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After charging the batteries for many hours with the 12V charger and PowerCheqs, I drove for about 5 miles and the low battery light came on. PakTrakr showed that the battery next to the most positive battery needed recharging. Apparent that battery is bad,....
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If the green LED is on, the slave MCU is enabled. The MAX690 keeps the memory contents during power off. No resouces of the slave MCU are used. Wenn a SAB-C515 is used, it is possible to develop programs for the AT89-family easily by changing simply the port....
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This is a simple circuit which outputs a voltage which is more than the input. This could be used to power 12v or 9v devices from a 6v system, or even 6v devices from a 1. 5v battery (see below). This circuit uses bog standard parts, without requiring a....
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Converting my 1958 Buick over to electric wipers with delay and automatic "wipe on wash" functionality, and in the process I`m trying to figure out how to integrate the new electricals with the entirely non-electric original wiper controls so the driver....
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You may need a different wiper motor in some cases, rebuilt units are typically available at the parts store for a reasonable cost. Once you have the parts and the manuals, it should be a simple matter of installing the right switch, motor, and (if needed)....
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The EMEM2 was invented by Dan Tracy. In a conversation with "Doug", the inventor of the large coil device, he commented that the EMEM2 does kill Lyme disease and that it is a lot of machine for the money. It has also been demonstrated to be useful for many....
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The Mainline ST-5 was originally Introduced in the RTTY JOURNAL in May, 1970. It has rapidly become one of the most popular demodulators for RTTY. As back issues have been un available for some time, the original article is being reprinted. For those....
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The word "demodulator" is becoming standard practice with commercial and military organizations. "Converters" are now often thought of with respect to units automatically changing Morse code to RTTY; changing 8-level to 5-level; changing 50 Baud to 45 Baud,....
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Tthe circuit has enjoyed popularity as a standalone booster and as a building block in larger circuits. While the circuit has its merits, we decided to further explore it to determine if it was a truly faithful solid-state version of the familiar input stage....
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A circuit diagram for an adjustable rpm switch. It ’s something you can use to activate solenoids for auxiliary ports, VDI, shift light, or anything else you can think of. The circuit is adapted from a rev-limiter circuit for rotaries. In particular, I ’d....
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You can get booster for fuel pumps to increase their rating, but is it possible to do anything to the wireing of an external pump to get it to flow LESS fuel Reason I ask is I am helping my brother out with an engine swap (admittidly, its not a rotary, or an....
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This one is V3. 0, for TII use, stock FC ignition, 24-2 style modified CAS, and 3-bar MAP sensor. It tests fine on the stim, so I`m hoping all is well. I`ll power up my test bench later, and test with an actual 24-2 style CAS just to be sure. All wiring is....
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Building your own Zapper. 1 Compositor 1 micro farad, C2, I like the un-polarized because it allows you not to worry about positive an negative sides. If you do get one with a longer leg that`s the positive, see schematic for proper placement. 1 resistor for....
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Computes the gain and the input and output resistances and automatically sends the results to the output file. To specify the transfer function, choose Setup from the Analysis menu and open the Transfer Function dialog box. In the Output Variable box specify....
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The back EMF voltage spikes produced by stepper motors (particularly higher voltage motors) can damage your PC`s printer port if connections are made incorrectly, flyback diodes are absent or connected in reverse, etc. The safest options are opto-isolated or....
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When you press a start button, the arduino picks a random 4 diget code and flashes lights to show the code. When you repeat the code in the other buttons, the XBee will send a message to the other XBee, which will ring the bell. int bell=5; void setup(){....
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This is the original Circuit Cellar ImageWise Transmitter that I started with. I disassembled the code and made it grab two half size images. This allowed me to get an image from the odd field and even field. I then wrote code to subtract the two fields....
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The project Thor was started at the High Voltage Institute of HUT (Helsinki University of Technology) on January 1999. Dr. Martti Aro is in charge of project supervision and Marco Denicolai of project development and implementation. Within this project a....
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The red connector is for an optional external antenna wire and the black connector is for a ground wire. The red is wired to secondary winding and the black is connected to the circuit ground plane. Additionally two by-pass capacitors (100n) are soldered....
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One of those smart cards that are often used for illegal viewing of encrypted video signals. It contains an Atmel AT90S8515A processor and an 8k EEPROM memory AT24C64, which gives the card adequate processing power for numerous other purposes. Other card....
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The Fluke interface diagram is an example of a typical microcontroller circuit. There is not really much to see, apart from the microcontroller itself. Nevertheless I`ll try to explain what`s happening here, because not everything is as obvious as it may....
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All PIC IR Decoders share the same, easy to build, hardware. All parts for this hardware are easily obtainable throughout the world. Building it shouldn`t take very much longer than one evening. At the heart of the diagram is the PIC16F84 processor. It is....
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IR remote control for my Nikon DSLR camera. Not that I absolutely need one, surely I don`t need it bad enough to get one for about ‚¬30 or ‚¬40 from e-bay. However it would make a nice little in-between project. Big Mike explains the very easy protocol used....
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Every IC on the I ²C bus requires a unique address. Usually such ICs can select from a set of 2 to 8 possible addresses to allow multiple chips of the same type on one bus. The SAA1064 can select from 4 different addresses by applying a specific voltage on....
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The UTP Cable Tester can be used for many purposes. Mainly to test a UTP network cables of course. However it can also be used to find the right cable in a large bundle of identical looking cables. In fact the circuit can be used or adapted to test any type....
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The SciSys Leonardo and Saitek Galileo and Renaissance chess computers could be connected to a PC via an OSA-Link cable. Such a cable is needed to run the OSA-4-Arena software and other tools. Unfortunately that cable is no longer available. Special....
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A Burrough`s B-7971 Nixie Tube clock that I built back in 1979 when I was a senior in High School. The digits are 2 ½ inches high which allowed me to read the clock from anywhere in my bedroom without needing to wear my glasses. The clock circuit is based on....
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All filter stages using a Virtual Ground will have the Virtual Ground DC potential on their outputs, while all stages having a resistive divider on their input (and no virtual Ground) will have the divider potential on their output. For supply currents of up....
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Magnetic stimulation is a non-invasive method of stimulating the brain and peripheral nervous system using induced currents. When used to stimulate the brain it is normally referred to as Transcranial Magnetic Stimulation or TMS. The basic principle is shown....
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Describes reading a thermistor using an Atmel ATtiny45 or ATMega168 microcontroller to drive two fans to cool a PC installed in a kitchen cabinet. Include a table for converting the BC1482 resistance to Fahrenheit....
The Flip-Flop Robot drives forward until it hits an obstacle, and then reverses until it hits another obstacle. This back-and-forth process continues indefinitely. By limiting the functionality to this very rudimentary behavior, it can be generated from an....
The simplest solution for implementing joystick control for a robot would be to program the actions in software in a microcontroller. But, since many readers prefer off-the-shelf parts, this circuit is going to be made with diodes, resistors, transistors,....
Most of my circuits still use 5 V regulated power for the chips, because 8-bit microcontrollers run faster and some sensors require 5 V. Since 5 V is more than enough for even a white LED, I`m not concerned with the voltage needed by a particular LED in use.....
The laser-pointer detection circuitry is able to determine when a laser light is aimed at a particular photosensor. If the laser is aimed at the top sensor, the comparator chip outputs on . If the laser is aimed at the bottom sensor, the comparator chip....
To understand how the 74AC14 PWM circuit works, let`s zoom in on the section of the schematic containing the trimpot, diodes, capacitor, and the first inverter logic gate. The capacitor is empty (discharged) when the power is first applied to the circuit.....
Discrete blinking LEDs are convenient, but the blink rate and blink duration are not configurable. I tried goofing around with using transistors, resistors, and capacitors to alter the blinking LED. In the end, I had so many extra electronic components that....
One of the first lessons that an electronics student learns is that an LED provides light from current flow. But, did you know that an LED put in backwards provides current flow from light Yes! It`s true. Hook up a high-quality ultra-bright red LED by itself....
This circuit adds a datasheet-compliant trigger signal, reversed polarity protection, optional test button, and optional battery operation. U1 L601E3 or MAC97A8 triac. 400 V, 1 A. When U1 is enabled, the + and - wires of the flash are electrically connected,....
To obtain the power supply graphs on the previous page, I didn`t stand outside for two days straight measuring the power sources with a voltmeter. Instead, the circuit itself is able to independently monitor the power sources with the addition of a few....
Need more current If you`ve got a larger motor waiting to be used, the Pololu High Current Motor Driver Board 14A 6V-16V is just what you need. Connect three digital lines to your microcontroller (five if you want error condition feedback), and you`re ready....
This is a very crude handdrawn schematic version 2. I`ll pop it into Protel later when I get the time. But it does give you a very handy overview of the circuit where it`s possible to charge from 2 different sources. Either by USB or normal charger. Also....
Figure shows a simplified representation of the Earth`s dipole field, it resembles the field due to a bar magnet. The field lines originate at the south magnetic pole and terminate at the north magnetic pole. The angle that this field makes when it....
This is a very simple circuit where the PIC and an internal 1kHz sinewave table do all the hard work of making an accurate sinewave. Then it needs only a few external parts for filtering. The sinewave has a very high frequency accuracy as it is generated....
After charging the batteries for many hours with the 12V charger and PowerCheqs, I drove for about 5 miles and the low battery light came on. PakTrakr showed that the battery next to the most positive battery needed recharging. Apparent that battery is bad,....
If the green LED is on, the slave MCU is enabled. The MAX690 keeps the memory contents during power off. No resouces of the slave MCU are used. Wenn a SAB-C515 is used, it is possible to develop programs for the AT89-family easily by changing simply the port....
This is a simple circuit which outputs a voltage which is more than the input. This could be used to power 12v or 9v devices from a 6v system, or even 6v devices from a 1. 5v battery (see below). This circuit uses bog standard parts, without requiring a....
Converting my 1958 Buick over to electric wipers with delay and automatic "wipe on wash" functionality, and in the process I`m trying to figure out how to integrate the new electricals with the entirely non-electric original wiper controls so the driver....
You may need a different wiper motor in some cases, rebuilt units are typically available at the parts store for a reasonable cost. Once you have the parts and the manuals, it should be a simple matter of installing the right switch, motor, and (if needed)....
The EMEM2 was invented by Dan Tracy. In a conversation with "Doug", the inventor of the large coil device, he commented that the EMEM2 does kill Lyme disease and that it is a lot of machine for the money. It has also been demonstrated to be useful for many....
The Mainline ST-5 was originally Introduced in the RTTY JOURNAL in May, 1970. It has rapidly become one of the most popular demodulators for RTTY. As back issues have been un available for some time, the original article is being reprinted. For those....
The word "demodulator" is becoming standard practice with commercial and military organizations. "Converters" are now often thought of with respect to units automatically changing Morse code to RTTY; changing 8-level to 5-level; changing 50 Baud to 45 Baud,....
Tthe circuit has enjoyed popularity as a standalone booster and as a building block in larger circuits. While the circuit has its merits, we decided to further explore it to determine if it was a truly faithful solid-state version of the familiar input stage....
Building your own Zapper. 1 Compositor 1 micro farad, C2, I like the un-polarized because it allows you not to worry about positive an negative sides. If you do get one with a longer leg that`s the positive, see schematic for proper placement. 1 resistor for....
Computes the gain and the input and output resistances and automatically sends the results to the output file. To specify the transfer function, choose Setup from the Analysis menu and open the Transfer Function dialog box. In the Output Variable box specify....
The back EMF voltage spikes produced by stepper motors (particularly higher voltage motors) can damage your PC`s printer port if connections are made incorrectly, flyback diodes are absent or connected in reverse, etc. The safest options are opto-isolated or....
When you press a start button, the arduino picks a random 4 diget code and flashes lights to show the code. When you repeat the code in the other buttons, the XBee will send a message to the other XBee, which will ring the bell. int bell=5; void setup(){....
This is the original Circuit Cellar ImageWise Transmitter that I started with. I disassembled the code and made it grab two half size images. This allowed me to get an image from the odd field and even field. I then wrote code to subtract the two fields....
The project Thor was started at the High Voltage Institute of HUT (Helsinki University of Technology) on January 1999. Dr. Martti Aro is in charge of project supervision and Marco Denicolai of project development and implementation. Within this project a....
The red connector is for an optional external antenna wire and the black connector is for a ground wire. The red is wired to secondary winding and the black is connected to the circuit ground plane. Additionally two by-pass capacitors (100n) are soldered....
One of those smart cards that are often used for illegal viewing of encrypted video signals. It contains an Atmel AT90S8515A processor and an 8k EEPROM memory AT24C64, which gives the card adequate processing power for numerous other purposes. Other card....
All PIC IR Decoders share the same, easy to build, hardware. All parts for this hardware are easily obtainable throughout the world. Building it shouldn`t take very much longer than one evening. At the heart of the diagram is the PIC16F84 processor. It is....
IR remote control for my Nikon DSLR camera. Not that I absolutely need one, surely I don`t need it bad enough to get one for about ‚¬30 or ‚¬40 from e-bay. However it would make a nice little in-between project. Big Mike explains the very easy protocol used....
Every IC on the I ²C bus requires a unique address. Usually such ICs can select from a set of 2 to 8 possible addresses to allow multiple chips of the same type on one bus. The SAA1064 can select from 4 different addresses by applying a specific voltage on....
The UTP Cable Tester can be used for many purposes. Mainly to test a UTP network cables of course. However it can also be used to find the right cable in a large bundle of identical looking cables. In fact the circuit can be used or adapted to test any type....
The SciSys Leonardo and Saitek Galileo and Renaissance chess computers could be connected to a PC via an OSA-Link cable. Such a cable is needed to run the OSA-4-Arena software and other tools. Unfortunately that cable is no longer available. Special....
A Burrough`s B-7971 Nixie Tube clock that I built back in 1979 when I was a senior in High School. The digits are 2 ½ inches high which allowed me to read the clock from anywhere in my bedroom without needing to wear my glasses. The clock circuit is based on....
All filter stages using a Virtual Ground will have the Virtual Ground DC potential on their outputs, while all stages having a resistive divider on their input (and no virtual Ground) will have the divider potential on their output. For supply currents of up....
Magnetic stimulation is a non-invasive method of stimulating the brain and peripheral nervous system using induced currents. When used to stimulate the brain it is normally referred to as Transcranial Magnetic Stimulation or TMS. The basic principle is shown....
