I ride my bike allot at night and sometimes I'm not sure if people can see me. This circuit will flash an incandescent light that you can purchase from Radio Shack. Adjust the VR's for your flash requirements and make sure that the lamp you use is designed to put out high brightness. The enclosure should be water tight. The Batteries can be replaced by a bike wheel generator and a diode. If you add the generator then you can still use rechargeable batteries and the batteries will charge while you are riding your bike. Copyright 2000...

The way that this circuit works is as follows. The AC line voltage is rectified by D1 and D2 which connects to a voltage doubler circuit made up of the two 22uf capacitors. The Flash Freq. Pot and the 10uf capacitor charge up which triggers the Diac and causes the triac to turn on. This allows the trigger transformer T1 to send a very High Voltage to the flash tube and lighting it. The flash timing is adjusted by the flash freq. pot. Copyright 1999 [url=http://home.maine.rr.com/randylinscott/index.html]Randy Linscott[/url]...

I have had many requests for this circuit. It was a very popular unit years ago. The basic idea of the project is to make different colored bulbs light at different frequencies of music. The circuit connects to the speaker outputs of your stereo or to the back of your speaker. The music passes through the transformer and the volume level is adjusted by the 5k ohm pot. Each light bulb is turn on by a different frequency of sound based on the resistor & capacitor combination in the gate circuit of the SCR. If the resistors R1, R2, or R3 are changed, the frequency of sound that will trigger...

This circuit was requested from an email. It will allow your car headlights to flash on and off at the same time or it will cause them to flash alternately. The circuit is based on the 555 timer. It is used in the astable mode. The 555 timer output will go high for an adjustable period of time and then turn off. It will then repeat the procedure. The time is adjusted by R1. To hook up the circuit to your car you must locate the positive wire from the fuse box to the headlights. Cut the wire and insert the relay contact and bypass switch. The bypass switch will allow you to bypass the relay...

The LED flasher circuits above operate on a single 1.5 volt battery. The circuit on the upper right uses the popular LM3909 LED flasher IC and requires only a timing capacitor and LED. The top left circuit, designed by Andre De-Guerin illustrates using a 100uF capacitor to double the battery voltage to obtain 3 volts for the LED. Two sections of a 74HC04 hex inverter are used as a squarewave oscillator that establishes the flash rate while a third section is used as a buffer that charges the capacitor in series with a 470 ohm resistor while the buffer output is at +1.5 volts. When the...

See image above Copyright 2006: [url=http://ourworld.compuserve.com/homepages/Bill_Bowden/]Bill Bowden[/url]...

In this circuit, an SCR is used to slowly vary the intensity of a 120 volt light bulb by controlling the time that the AC line voltage is applied to the lamp during each half cycle. [b:843a2f46b8]Caution:[/b:843a2f46b8] The circuit is directly connected to the AC power line and should be placed inside an enclosure that will prevent direct contact with any of the components. To avoid electrical shock, do not touch any part of the circuit while it is connected to the AC power line. A 2K, 10 watt power resistor is used to drop the line voltage down to 9 volts DC. This resistor will dissipate...

This is basically a Schmitt Trigger circuit which receives input from a cadmium sulfide photo cell and controls a relay that can be used to switch off and on a street lamp at dawn and dusk. I have built the circuit with a 120 ohm/12 volt relay and monitored performance using a lamp dimmer, but did not connect the relay to an outside light. The photo cell should be shielded from the lamp to prevent feedback and is usually mounted above the light on top of a reflector and pointed upward at the sky so the lamp light does not strike the photo cell and switch off the lamp. The photo cell is...

The LED circuit above is an example of using 25 white LEDs in series connected to the 120VAC line. It can be modified for more or less LEDs by changing the R value. The exact resistance value will depend on the particular LEDs used. In operation, a DC voltage of around 170 is produced from the bridge rectifier and 50uF capacitor. The capacitor value is not critical and can be anything from 20uF or more. The capacitor voltage must be 200 volts or more. You can find 200 volt 470uF capacitors in old PC computer power supplies. To find the resistor value and wattage, multiply the number of...

Similar to the [url=http://www.circuitdb.com/show.php?cid=161]Automatic 12 Volt Lamp Fader[/url], the sunset lamp comes on at full brightness and then slowly fades out over 1.5 hours time and stays off until power is recycled. Copyright 2003 [url=http://ourworld.compuserve.com/homepages/Bill_Bowden/]Bill Bowden[/url]...

In this circuit, a 120VAC lamp is slowly illuminated over a approximate 20 minute period. The bridge rectifier supplies 120 DC to the MOSFET and 60 watt lamp. A 6.2K, 5 watt resistor and zener diode is used to drop the voltage to 12 volts DC for the circuit power. The bridge rectifier should be rated at 200 volts and 5 amps or more. In operation, a 700 Hz triangle waveform is generated at pin 1 of the LM324 and a slow rising voltage is obtained at pin 8. These two signals are compared at pins 12 and 13 to produce a varying duty cycle rectangular waveform at pin 14, which controls the MOSFET...

The LED traffic Light circuit controls 6 LEDs (red, yellow and green) for both north/south directions and east/west directions. The timing sequence is generated using a CMOS 4017 decade counter and a 555 timer. Counter outputs 1 through 4 are wire ORed using 4 diodes so that the (Red - North/South) and (Green - East/West) LEDs will be on during the first four counts. The fifth count (pin 10) illuminates (Yellow - East/West) and (Red - North/South). Counts 6 through 9 are also wire ORed using diodes to control (Red - East/West) and (Green - North/South). Count 10 (pin 11) controls (Red -...

The question sometimes comes up of how to cascade 4017 decade counters for more than 10 sequencial stages. The LED sequencer above shows a possible solution using a few extra parts. When power is applied, the 15K resistor and 10uF cap at pin 15 will reset the counters to the zero count where pin 3 is at +12 and all other outputs are at zero. The 2 diodes (1n914) and 15 resistor form a AND gate so the clock pulse will be passed to the right side counter when the sequence starts. When the right counter reaches the 10th count, pin 11 will move high enabling the AND gate on the right to pass...

The circuit above illustrates powering a LED (or two) from the 120 volt AC line using a capacitor to drop the voltage and a small resistor to limit the inrush current. Since the capacitor must pass current in both directions, a small diode is connected in parallel with the LED to provide a path for the negative half cycle and also to limit the reverse voltage across the LED. A second LED with the polarity reversed may be subsituted for the diode, or a tri-color LED could be used which would appear orange with alternating current. The circuit is fairly efficient and draws only about a half...

This circuit above can drive 25 small Xmas lights. The lights operate at about 200mA and 3 volts. The supply voltage is set to 5 volts and the 4017 counter output will drop about a volt using the 2N3053 transistors. The voltage on the emitters of the rows transistors will be about 0.7 volts less than the base so the lamp voltage will be about 3 volts. You can adjust the supply voltage for the desired current if necessary. It works the same way as the LED version but you need diodes in series with each light. Most any small diode rated at 500mA or more should work. I used 1N4001 diodes....

The circuit above illustrates using a 10x10 matrix to sequence up to 100 LEDs with just three ICs and 20 transistors. The two 4017 decade counters control the 10 rows and 10 columns so that one LED is selected depending on the output of the decade counters. The LED circuit is drawn showing 25 LEDs and 10 transistors but can be expanded up to a 100 by using sucessive stages of the 4017 counters. For example, to expand the circuit to 60 LEDs for displaying minutes or seconds of a clock, the rows counter could be reset from pin 12 (carry out) rather than pin 1 as shown, and the columns...

The bi-directional sequencer uses a 4 bit binary up/down counter (CD4516) and two "1 of 8 line decoders" (74HC138 or 74HCT138) to generate the popular "Night Rider" display. A Schmitt Trigger oscillator provides the clock signal for the counter and the rate can be adjusted with the 500K pot. Two additional Schmitt Trigger inverters are used as a SET/RESET latch to control the counting direction (up or down). Be sure to use the 74HC14 and not the 74HCT14, the 74HCT14 may not work due to the low TTL input trigger level. When the highest count is reached (1111) the low output...

The circuit below uses a hex Schmitt Trigger inverter (74HC14) and two 8 bit Serial-In/Parallel-Out shift registers (74HCT164 or 74HC164) to sequence 16 LEDs. The circuit can be expanded to greater lengths by cascading additional shift registers and connecting the 8th output (pin 13) to the data input (pin 1) of the succeeding stage. A Schmitt trigger oscillator (74HC14 pin 1 and 2) produces the clock signal for the shift registers, the rate being approximately 1/RC. Two additional Schmitt Trigger stages are used to reset and load the registers when power is turned on. Timing is not critical,...

Here is a 12 volt / 2 amp lamp dimmer that can be used to dim a standard 25 watt automobile brake or backup bulb by controlling the duty cycle of a astable 555 timer oscillator. When the wiper of the potentiometer is at the uppermost position, the capacitor will charge quickly through both 1K resistors and the diode, producing a short positive interval and long negative interval which dims the lamp to near darkness. When the potentiometer wiper is at the lowermost position, the capacitor will charge through both 1K resistors and the 50K potentiometer and discharge through the lower 1K...

This circuit is similar to the LED clock using 12 neon indicator lamps instead of LEDs. It operates from 2 high capacity ni-cad cells (2.5 volts) which keep it going for a couple weeks. High voltage (70 volts) for the neon lamps is obtained from a small switching power supply using a 74HC14 Schmitt trigger squarewave oscillator, high voltage switching transistor, and 10 mH high Q inductor. Most any small PNP transistors can be used that have a C/E voltage rating of 80 or more. The inverter stage (pins 5,6) is not needed and is just an extra stage. An adjustable low frequency oscillator made...

In this circuit, one, two or three neon indicator bulbs can be made to flash in sequence at rates determined by the R and C values. In the single stage circuit, using one lamp, the capacitor charges through the resistor until the ionization potential of the neon is reached (about 70 volts) and then discharges quickly through the lamp until the voltage falls below what is needed to sustain the lamp which is approximately 45 volts. The cycle then repeats at a rate of about 3 Hz for values shown. Smaller R or C values increase frequency, larger values decrease frequency. All capacitors should be...

This circuit provides a visual 9 second delay using 10 LEDs before closing a 12 volt relay. When the reset switch is closed, the 4017 decade counter will be reset to the 0 count which illuminates the LED driven from pin 3. The 555 timer output at pin 3 will be high and the voltage at pins 6 and 2 of the timer will be a little less than the lower trigger point, or about 3 volts. When the switch is opened, the transistor in parallel with the timing capacitor (22uF) is shut off allowing the capacitor to begin charging and the 555 timer circuit to produce an approximate 1 second clock signal to...

This inverter is very easy to construct, reliable, and even powerful enough to light up a 15W florescent tube (if you cool your transistor well). The only hard-to-find piece of this baby is the so-called yellow inverter transformer. It's a miniature high frequency transformer that has a 25mm x 20mm x 5mm ferrite core, 30 turns of primary, 15 turns of feedback, and 250 turns of secondary all concentric, wound on plastic frame than wrapped with a 'yellow' adhesive tape. If you can't find it in your local electronic shops then search for old portable rechargeble florescent lanterns since they...

See image above Copyright 2006: [url=http://ourworld.compuserve.com/homepages/Bill_Bowden/]Bill Bowden[/url]...

In the circuit above, 60 individual LEDs are used to indicate the minutes of a clock and 12 LEDs indicate hours. The power supply and time base circuitry is the same as described in the 28 LED clock circuit above. The minutes section of the clock is comprised of eight 74HCT164 shift registers cascaded so that a single bit can be recirculated through the 60 stages indicating the appropriate minute of the hour. Only two of the minutes shift registers are shown connected to 16 LEDs. Pin 13 of each register connects to pin 1 of the next for 7 registers. Pin 6 of the 8th register should connect...

This circuit can be used to slowly illuminate and fade a pair of LEDs, or with the addition of a second transistor (PNP) the circuit will fade two pairs of LEDs out of phase so that one pair gets brighter while the other grows dimmer. The dual transistor version is shown below the single transistor circuit. Most any op-amp should work, I used the 1458 dual op-amp in the single transistor circuit and the LM324 quad op-amp in the dual transistor version. The two spare op-amps in the LM324 package could be used for a second circuit running at a different rate which would allow using four pairs...

This is a programmable clock timer circuit that uses individual LEDs to indicate hours and minutes. 12 LEDs can be arranged in a circle to represent the 12 hours of a clock face and an additional 12 LEDs can be arranged in an outer circle to indicate 5 minute intervals within the hour. 4 additional LEDs are used to indicate 1 to 4 minutes of time within each 5 minute interval. The circuit is powered from a small 12.6 volt center tapped line transformer and the 60 cycle line frequency is used for the time base. The transformer is connected in a full wave, center tapped configuration which...

The 555 circuit below is a flashing bicycle light powered with four C,D or AA cells (6 volts). Two sets of 20 LEDs will alternately flash at approximately 4.7 cycles per second using RC values shown (4.7K for R1, 150K for R2 and a 1uF capacitor). Time intervals for the two lamps are about 107 milliseconds (T1, upper LEDs) and 104 milliseconds (T2 lower LEDs). Two transistors are used to provide additional current beyond the 200 mA limit of the 555 timer. A single LED is placed in series with the base of the PNP transistor so that the lower 20 LEDs turn off when the 555 output goes high during...

A simple rotating display. Just spin and enjoy. While the "Air display" is rotating, it writes the message on the air. Because the "persistence of the vision", you will be able to read the message. Circuit, see JP6293E.gif. Download the HEX file - Program the PIC with JP6293E.hex. Algorithm - Build your own Air Display using code.txt. The operation is super simple and you don't need an user manual. Press the button to turn it on. Press the button to change the message and press the button to turn it off. NOTE: Use high brighness leds to use it in...

The easiest way to control a RGB Led. tinyRGB uses an ATMEL Attiny15L (8pin uC) to control a standard RGB Led. R1 is a pullup Resistor for Reset generation (should be about 10k). R3 to R5 depend on the LED you are using. You can calculate the resistor as followed: [list:be74d5d7a1]Rx = (Vcc-Vf)/Im[/list:u:be74d5d7a1] [Vcc: Volatge of power supply, Vf: Vorward Voltage of the Diode, Im: Max current of LED or AVR pin (20mA)] The software is written in Assembler (avra under Linux, should be compatible to AVR Studio). Timer0 is used to generate interrupts at about 30kHz. This...

[b:215db9aed6]Astonishing effect 4.5V supply[/b:215db9aed6] [b:215db9aed6]Circuit operation:[/b:215db9aed6] This circuit operates a LED in pulsing mode, i.e. the LED goes from off state, lights up gradually, then dims gradually, etc. This operation mode is obtained by a triangular wave generator formed by two op-amps contained in a very cheap 8 pin DIL case IC. Q1 ensures current buffering, in order to obtain a better load drive. R4 & C1 are the timing components: using the values shown in the parts list, the total period is about 4...

You see LED chasers everywhere, in TV shows (Knight Rider), movies, and store windows. This schematic is my version of a simple 10 LED chaser. There is no 555 timer used because at my local electronics store they are over $4 Cdn. Instead, an oscillator made up of two sections of a 4011 NAND gate is employed. This chip is very inexpensive and extremely common. Notes: 1. Use R2 to adjust the "chase rate". 2. You may need to use a lower value resistor if you wish to use blue LEDs. Try 220 Ohm. 3. You can also use incandescent lamps instead of LEDs. Use transistors to drive them by...