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 12V to +/- 30V DC to DC Converter circuit Diagram This is a DC to DC converter for car power amplifier. 12V input generates +30V and -30V output for preamp or power amplifiers. Circuit uses SG3525 IC, Mosfets and switching power supply.

5V Regulated Power Supply Circuit Diagram is a small +5V power supply, which is useful when experimenting with digital electronics. Small inexpensive wall tranformers with variable output voltage are available from any electronics shop and supermarket. Those transformers are easily available, but usually their voltage regulation is very poor, which makes then not very usable for digital circuit experimenter unless a better regulation can be achieved in some way. The following circuit is the answer to the problem. This circuit can give +5V output at about 150 mA current, but it can be increased to 1 A when good cooling is added to 7805 regulator chip. The circuit has overload and thermal protection. The capacitors must have enough high voltage rating to safely handle the input voltage feed to circuit. The circuit is very easy to build for example into a piece of veroboard.  5V Regulated Power Supply Circuit Diagram Parts: C1 = 100uF-25V electrolytic capacitor, at least 25V voltage r...

The IC is a quad 2 input “AND” gate, a CMOS 4081. These gatesonly produce a HIGH output, when BOTH the inputs are HIGH. Whenthe key wired to `E` is pressed, current through R1 and D1switches Q5 on. The relay energises; and Q5 is `latched on` byR8. Thus, the Alarm is set by pressing a single key, say one ofthe tw1o non-numeric symbols.The alarm will switch off when the 4 keys connected to“A,B,C,D” are pushed in the right order. The circuit worksbecause each gate `Stands` upon its predecessor.If any key otherthan the correct key is pushed, then gate 1 is knocked out of thestack, and the code entry fails.  Pin 1 is held high by R4. This`Enables` gate 1; and when button `A` is pressed, theoutput at pin 3 will go high. This output does tw1o jobs.It locksitself `ON` through R2 and it `Enables` gate 2, by taking pin 5,high. Now, if `B` is pressed, the output of gate 2, at pin 4will go high. This output does tw1o jobs. It locks itself `ON`through R3 and it `Enables` gate 3 by taking pin 12...

Build a Simple Electronic Music Maker Circuit Diagram . This electronic music maker uses an astable oscillator circuit that is controlled by a photocell. The light falling on the photo cell controls the tone. By mounting the circuit in a box, you can control light-reading PCI with your hand. Simple Electronic Music Maker Circuit Diagram Sourced By: Circuitsstream

This is a simple 300W Subwoofer Power Amplifier Circuit Diagram. This is an amplifier circuit that is formed from a transistor amplifier miraculous. This circuit is used in the speaker subwoofer with 300W maximum power on each side. To apply it, can be used in the room that is not too large, like the car. And the voltage needed between 25 to 42 Volt DC. 300W Subwoofer Power Amplifier Circuit Diagram  

4 Transistor 500mW FM Transmitter Circuit Diagram As shown, the audio ascribe is a microphone, which uses 2 x 2N3904 as the microphone audio preamplifier. The audio/mic ascribe akin is adjustable by agency of a 5k preset / potentiometer. The ambit uses a Colpitts oscillator for abundance generation, which is chargeless active and operates at the axiological abundance i.e. no circuitous abundance multiplication or control. The abundance affability basic of the ambit consists of 2 5pF (picoFarad) capacitors and a distinct 10uH (micro-Henry) inductor. These apparatus can be adapted if a change in abundance is appropriate - conceivably alike replaced with capricious capacitors (if you're up to the challenge). An achievement RF amplifier takes the abundance produced by the Colpitts oscillator and amplifier to about about the 500mW (0.5 Watt) ambit - so this is the almost achievement ability of this FM transmitter. You are brash that back this transmitter operates at the axiological fr...

This is a simple t imed beeper circuit diagram of beeper using 555 timer. This circuit can be employed to energize lights, horn, or other signaling device at any desired interval when the mercury switch is triggered. Since the current handling capability of mercury switch is not so high, an SCR is used to handle current drawn by the 555 timer circuit . Chose the SCR  current rating of 500mA at minimum to safely drive the 555 IC and the relay. The relay is not needed when the current drawn by alarm is less than 200mA, in this case the alarm can be installed to directly replace the relay coil.  Here is the schematic diagram of the circuit. 555-IC Timed Beeper Circuit Diagram

Zener diode ZD1 senses the supply, and should the supply rise above 6 V, Ql will turn on. In turn, Q2 conducts clamping the rail. Subsequent events depend on the source supply. It will either shut down, go into current limit or blow its supply fuse. None of these will damage the TTL chips. The rating of Q2 depends on the source supply, and whether it will be required to operate continuously in the event of failure. Its current rating has to be in excess of the source supply. Over voltage protection for logic Circuit Diagram

Overview This is an IR remote control for Nikon cameras. It is compatible with the Nikon ML-L3 remote control. Supported cameras include: D40, D40X, D50, D60, D70, D70s, D80, Coolpix 8400 8800. This design is based on an idea from http://www.bigmike.it/ircontrol/. Hardware The circuit is extremely simple: an ATtiny13V, button, transistor, resistor, IR diode and 3V battery. You could even omit the transistor and resistor, and connect the IR diode directly to the ATtiny13V, but that will limit the LED current and therefor the range. I chose to power the circuit permanently, and connect the button to an input, instead of controlling the power with the button. This ensures that the IR sequence is always completely sent, even when you release the button too early, and that contact bounce may be filtered. The standby power consumption is so low, about the same as the self-discharge rate of the lithium battery, that this does not really affect the battery life. The internal oscillator of the...

Using the bilateral properties of a balanced mixer this transvertcr will produce 6-m output with 2-m inputs. Y1 is a 90-MHz crystal. Note that the input on 2 m is 143 to 144 MHz for 53 to 54-MHz output. This avoids possibility of extraneous 2-m reception during receive periods. If your radio will not transmit below 144 MHz, then use a 93- or 94-MHz crystal frequency. 2M 6M Transverter Circuit Diagram Build a 2M 6M Transverter Circuit Diagram

Description Here’s the circuit of a multi-switch input musical doorbell (shown in Fig.1). The circuit is built around the popular and less expensive quad D-latch CD4042B (IC1). When switch S6 is pushed to ‘on’ condition, the circuit gets +9V and the four data inputs (D1 through D4) of ICI are in low state because these are tied to ground via resistors R1 through R4. Polarity input (POL) pin 6 of IC1 is also pulled down by resistor R5. Circuit Diagram Clock input (pin 5) of the quad D-latch is wired in normally low mode and hence all the four outputs (Q0 through Q3) have the same states as their corresponding data inputs. As a result, LED1 through LED4 are in off condition. There are four switches fitted at four different doors/gates outside the home and a monitoring panel (as shown in Fig. 2) in the common room of the home. If any switch is pressed by a visitor (for example switch S1 at d...

Description Superheterodyne receivers have been mass-produced since around 1924, but for reasons of cost did not become successful until the 1930s. Before the second world war other, simpler receiver technologies such as the TRF receiver and the regenerative receiver were still widespread. The circuit described here is based on the old technology, but brought up-to-date a The most important part of the circuit is the input stage, where positive feedback is used to achieve good sensitivity and selectivity. The first stage is adjusted so that it is not quite at the point of oscillation. This increases the gain and the selectivity, giving a narrow bandwidth. To achieve this, the potentiometer connected to the drain of the FET must be adjusted very carefully: optimal performance of the receiver depends on its setting. In ideal conditions several strong stations should be obtainable during the day using a 50 cm antenna. At night, several times this number should be obtainable. The frequency...

The LP2951 regulator is manufactured by National Semiconductors. The choice of values is from an application note Battery Charging , written by Chester Simpson. Diode D1 can be any diode from the 1N00x series, whichever is conveniently available. It functions as a blocking diode, to prevent a back flow of current from the battery into the LP2951 when the input voltage is disconnected. Charging current is about 100+mA, which is the internally-limited maximum current of the LP2951. For those wondering, this is compatible with just about any single-cell li-ion battery since li-ion can generally accept a charging current of up to about 1c (i.e. charging current in mA equivalent to their capacity in mAh, so a 1100mAh li-ion cell can be charged at up to 1100mA and so on). Li-Ion Battery Charger Circuit Diagram A lower charging current just brings about a correspondingly longer charge time. IMHO 100mA is quite low, low enough that the circuit can be used for an overnight charger for many typ...

This 2M 6M Transverter Circuit Diagram Using the bilateral properties of a balanced mixer this transvertcr will produce 6-m output with 2-m inputs. Y1 is a 90-MHz crystal. Note that the input on 2 m is 143 to 144 MHz for 53 to 54-MHz output. This avoids possibility of extraneous 2-m reception during receive periods. If your radio will not transmit below 144 MHz, then use a 93- or 94-MHz crystal frequency. 2M 6M Transverter Circuit Diagram

This is a simple Inexpensive car Protection Unit Circuit Diagram. This circuit to protect car stereo, etc from pilferage that costs less and requires no adjustments in the car but a good car cover. Place the circuit at your bedside and bring the two wires from the unit to the car (parked outside your home) and connect one wire-end to the cover and the other to the ground, with both wire-ends shorted by some weight such as a brick. So outwardly the mechanism is not visible. Circuit of car protection unit with alarm If someone tries to remove the cover, the alarm of the circuit starts sounding to alert you. The alarm can be switched off by resetting it using switch S1. The car protection circuit comprises two timer ICs: one for the alarm circuit (see IC2 in Fig.1) and the other to indicate that the battery has taken over as the power source (see IC3 in Fig. 2). Normally, the protector operates off AC mains and the battery takes over only when mains fail. As the battery current is not...

Normally, chargers available in the market do not have any sort of control except for a ro-tary switch that can select different tap-pings on a rheostat, to vary the charging current. This type of control is not adequate because of the irregular fluctuations in the mains supply, rendering the control ineffective.  A simple circuit intended for automatic charging of lead-acid batteries is presented here. It is flexible enough to be used for large capacity inverter batteries. Only the rating of transformer and power transistor needs to be increased. Circuit diagram : Automatic Battery Charger Circuit Diagram   The circuit has been basically designed for a car battery (about 40 Ah rating), which could be used for lighting two 40W tube lights. The circuit includes Schmitt trigger relay driver,float charger,and battery voltage monitor sections.  The Schmitt trigger is incorporated to avoid relay chattering. It is designed for a window of about 1V. During charging, when the ...

Imagine for aquarium lighting that gives a natural look, which is automatic and still use LED bulbs. That must cost a fortune, but even if you build a circuit of LED lighting that turns on automatically at sunset, off at dawn and switches the white, blue and green to give a different touch to the aquarium can get cheapie as in the above circuit. The interrupt circuit uses an LDR light sensor as making automatic switching, activating IC1 CD4060 which is a binary counter with 10 outputs, mixing colors and creating a colorful beautiful to the bottom of the aquarium tank.   Automatic Lighting Aquarium Circuit Diagram

This is a Simple 555 Tester Circuit Diagram. The IC 555 is a widely used timers, control circuits, PWM, alarms, etc.. Often we set up a circuit that does not work or works differently than expected, this time the ideal is a test circuit for this IC.  This test circuit 555 is connected as an astable multivibrator when the button switch S1 is pressed, the LEDs D1 and D2 flash alternately. Ie, when the output is high D2 will light when the output is low D3 will light, and the other a Hi Lo. The speed of flashes is determined by the components R1, R2 and C1.Pressing the S1 test the 555 starts and any change in the IC flashes may consider to be defective.

This article should satisfy those who might want to build a low power FM transmitter. It is designed to use an input from another sound source (such as a guitar or microphone), and transmits on the commercial FM band - it is actually quite powerful, so make sure that you don't use it to transmit anything sensitive - it could easily be picked up from several hundred metres away. The FM band is 88 to 108MHz, and although it is getting fairly crowded nearly everywhere, you should still be able to find a blank spot on the dial. NOTE: A few people have had trouble with this circuit. The biggest problem is not knowing if it is even oscillating, since the frequency is outside the range of most simple oscilloscopes. See Project 74 for a simple RF probe that will (or should) tell you that you have a useful signal at the antenna. If so, then you know it oscillates, and just have to find out at what frequency. This may require the use of an RF frequency counter if you just cannot locate the ...

This inverter circuit can provide up to 800mA of 12V power from a 6V supply. For example, you could run 12V car accessories in a 6V (British?) car. The circuit is simple, about 75% efficient and quite useful. By changing just a few components, you can also modify it for different voltages.  6V to 12V Converter Circuit Diagram Parts R1, R4 2.2K 1/4W Resistor R2, R3 4.7K 1/4W Resistor R5 1K 1/4W Resistor R6 1.5K 1/4W Resistor R7 33K 1/4W Resistor R8 10K 1/4W Resistor C1,C2 0.1uF Ceramic Disc Capacitor C3 470uF 25V Electrolytic Capcitor D1 1N914 Diode D21N4004 Diode D3 12V 400mW Zener Diode Q1, Q2, Q4 BC547 NPN Transistor Q3 BD679 NPN Transistor L1 See Notes MISC Heatsink For Q3, Binding Posts (For Input/Output), Wire, Board Notes 1. L1 is a custom inductor wound with about 80 turns of 0.5mm magnet wire around a toroidal core with a 40mm outside diameter. 2. Different values of D3 can be used to get different output voltages from about 0.6V to around 30V. Note that at higher voltages...