Build a 25W Class A Power Audio Amplifier Circuit Diagram

This is the 25W Class-A power audio amplifier circuit. The output devices are MJL4281A (NPN) and MJL4302A (PNP), and have high bandwidth, fantastic SOA (safe operating area), high linearity and high gain. Driver transistors are MJE15034 (NPN) and MJE15035 (PNP). All devices are rated at 350V, using the power transistors having a 230W dissipation and the drivers are 50W.

25W Class-A Power Audio Amplifier Circuit Diagram

•  The supply voltage must be a maximum of ±25V. This supply is simply obtained from a 20-0-20V transformer, recommended current is 1A.
•  All resistors ought to be 1/4W or 1/2W 1% metal film for lowest noise, with the exception of R9, R10 and R15 which ought to be 1/2W varieties, and R13, R14 have to be 5W wirewound.
•  Using the suggested and advised 25V supplies, Q4 will typically not need a heatsink. The output drivers (Q5 and Q6) recommended to use a heatsink, even though it doesn’t have to be big.

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Build a Tesla Coil Wiring diagram Schematic

Build a Tesla Coil Circuit Diagram. The Tesla coil described here can.generate 25,000 V. So, even though the output current is low, be very careful! The main component is a flyback transformer from a discarded TV. A new primary windin_g is needed. Begin by winding 5 turns of #18 wire on the core. Then, twist a loop in the wire, and finish by winding five more turns. 

Wrap with electrical tape, but leave the loop exposed. A four-tum winding must be wound over the ten-turn winding that you`ve just finished.That is done the same way. First wind two turns of# 18 wire, then make a loop, and finish by winding two more turns. Again, wrap the new winding with electrical tape, leaving the loop exposed. When the windings are finished, the two loops shouldn`t be more than 1/.-inch apart, but take care that they do not touch. Connect a 240-U resistor between the two loops. 

The modified transformer now should look like the one shown. Connect the transformer as shown. The 27 -U resistor and two transistors should be mounted on a heatsink and must be insulated from it. The output of the high-voltage winding should begin to oscillate as soon as the schema is connected to a 12-V de power supply. Ifit does not, reverse the connections to the base leads of the transistors. In normal operation, you should be able to araw l-inch sparks from the high-voltage lead using an insulated screwdriver.

Tesla Coil Circuit Diagram

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Build a Differential Instrumentation Amplifier Wiring diagram Schematic

Build a Differential Instrumentation Amplifier Circuit Diagram. An instrumentation amplifier is a type of differential amplifier that has been outfitted with input buffer amplifiers, which eliminate the need for input impedance matching and thus make the amplifier particularly suitable for use in measurement and test equipment.This schema relies on extremely high input impedance for effective operation. The HA-5180 with its JFET input stage, performs well as a preamplifier. 

 Differential Instrumentation Amplifier Circuit Diagram

The standard three amplifier configuration is used with very close matching of the resistor ratios R5/R4 and (R7 + R8)/R6, to insure high common-mode rejection (CMR). The gain is controlled through R3 and is equal to 2RI/R3. Additional gain can be had by increasing the ratios R5!R4 and (R7 + R8)!R6. The capacitors C1 and C2 improve the ac response by limiting the effects of transients and noise. 

Two suggested values are given for maximum transient suppression at frequencies of interest. Some of the faster DVM`s are operating at peak sampling frequency of 3-kHz, hence the 4-kHz, low-pass time constant. The 40kHz, low-pass time constant for ac voltage ranges is an arbitrary choice, but should be chosen to match the bandwidth of the other components in the system. C1 and C2 might however, reduce CMR for ac signals if not closely matched. Input impedances have also been added to provide adequate de bias currents for the HA-5180 when open-schemaed.

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Build a High Voltage Inverter Wiring diagram Schematic

The High Voltage Inverter Circuit Diagram converts a de voltage (V +) to a high-amplitude square wave in the audio-frequency range. The dual timer, IC2, provides an inexpensive alternative to the traditional transformer for providing complementary base drive to the power transistors, Ql and Q2. You can convert a 6 to 12 V battery output, for example, to an ac amplitude, which is limited primarily by the power rating of transformer Tl. 

Connect timer IC1 as an oscillator to provide a symmetrical square-wave drive to both inputs of IC2. The timing components, R2 and Cl, produce a 2.2-kHz output frequency. By connecting half of IC2 in the inverting mode and the other half in noninverting mode, the timer`s outputs alternately drive the two transistors. 

 Build a High Voltage Inverter Circuit Diagram

You can operate the audio-output transformer, Tl, as a step-up transformer by connecting it backwards using the output winding as an input. The transformer delivers an output voltage across RL of 4 x N x V+V pk-pk, where Nis the transformer turns ratio. For the schema shown, the output swing is 100 x V+V pk-pk.

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Easy Build RF Transmitter

This schema most likely the easiest and simplest radio transmitter which you will get anyplace. It uses total of 5 components and could be built into a really compact space. Its very good for science fair projects or other science related projects in which a small range transmission is useful.

It works on 1.5 to 3 V, with small hearing aid battery packs or lithium "coin" cells becoming excellent. A thermistor or photoresistor may be inserted in series with R1 to get a various output frequency depending on the input.

The frequency may also be adjusted by modifying the value of C1. A 2N2222 transistor is highly recommended, but you are able to try out other types as well. Performance is likely to vary from type to type as well as from transistor to transistor. L1 is 20 to 30 turns of thin magnet wire (24 to 32 ga.) close wound about a 1/8 to 1/4" diameter non-conductive form. The coil is normally tapped 1/3 of the way from one end and also the tap connected to the emitter of Q1. Try out with all of the values in this particular schema. Nothing is vital, but the result may be varied considerably. Read More

Build a 4 18Mhz Converter Wiring diagram Schematic

Build a 4-18Mhz Converter Circuit Diagram. The unit consists of RF amplifier Q1, local oscillatorQ2, and mixer Q3. The two bands are covered without a band switch by using an i-f or 3.5 MHz. The oscillator range is 7.5 to 14.5 MHz. Incoming signals from 4 to 11 MHz are mixed with the oscillator to produce the 3.5-MHz i-f.

Signals from 11 to 18 MHz are mixed with the oscillator to also produce an i-f of 3.5 MHz. At any one oscillator frequency, the two incoming signals are 7 MHz apart. Rf amplifier input Cl/L1 comprises a high-Q, lightly loaded, tuned schema; this is essential for good band separation.

Build a 4-18Mhz Converter Circuit Diagram

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Build a Uhf TV Preamplifier Wiring diagram Schematic

Build a UHF TV Preamplifier Circuit Diagram. An inexpensive. antenna-mounted, UHF TV preamplifier can add more than 25 dB of gain. The first stage of the preamp is biased for optimum noise, the second stage for optimum gain. Ll, L2 strip line `` J../8 part of PC board.

UHF TV Preamplifier Circuit Diagram

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Build a Hv Power Supply With 9 To 15Vdc Input Wiring diagram Schematic

Build a Hv Power Supply With 9 To 15Vdc Input Circuit Diagram. This Hv Power Supply is The combination Hartley oscillator/step-up transformer shown in A can generate significant negative high voltage, especially if the voltage output of the transformer is multiplied by the schema in B. 

Simple Hv Power Supply With 9 To 15Vdc Input Circuit Diagram

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