TDA2040 - 20W HI-FI Audio Amplifier

Here the hi-fi power amplifier circuit which will deliver 20W power output. This amplifier circuit use single power IC TDA2040 and a few external components.

Detailed explanation about this 20W Power Amplifier

Simple FM Radio Receiver Circuit with TDA7021T

Here the simple FM radio receiver circuit built based single IC TDA7021T.

Component Parts List:

R1 = 8kΩ2 R2 = 10kΩ R3 = 390Ω C1,C3 = 10nF C2,C6,C9,C16 = 100nF C4 = 33pF C5 = 25pF trimmer (Murata type TZB4Z250AB10R00) C7,C10 = 1nF5 C8 = 820pF

C11 = 1nF C12 = 68pF C13 = 220pF C14 = 47μF 10V (Nichicon UWX1A470MCL1GB 5.5mmL chip type) C15 = 3nF3 L1 = 36nH (4 turns 0.5mm silver-plated wire, inside diameter 4mm; length 7mm) L2 = 1μH, SMD case 0805 (fres > 300 MHz) IC1 = TDA7021T (SMD in SO16 case)

Complete explanation, visit this site

AM Receiver circuit with MK484

This is a AM Receiver with single IC MK484. If your are interested to build this radio circuit, you may buy the kits include the component part list at kitsrus.com.

Part list:

R9, R10_________ 6R8 R6_____________ 100R R3_____________ 1K R1_____________ 4K7 R7_____________ 5K6 R4_____________ 10K R2_____________ 100K R5_____________ 150K R8_____________ 820K Pot_____________ 10K log pot Coil & ferrite bar set

C7______________ 470p ceramic C, C4, C5, C6_____ 470nF monoblock C2______________ 100nF monoblock C3, C8___________ 100uF electrolytic capacitor VariCap__________ 60/160 AM tuning cap D1, D2, D3, D4____ 1N4148 diode Q1, Q3___________ BC548 Q2______________ BC558 IC1_____________ MK484 AM radio IC TO92 Speaker__________ 0.5 or 1W, 8 ohm speaker

Visit this AM Radio Receiver for more explanation.

Really Simple LED Flasher with LM3909

This is a very -very easy and simple LED flasher circuit with only needs three components that are: a flasher IC, a LED and a electrolytic capacitor.

Component list:

LED1_________Red LED
C1___________100uf/16V
IC1__________LM3909

Very nice for electronics newbie.. :)

Really Simple Audio Pre-Amplifier

This pre-amp circuit is very simple. It's just need 1 active component (transistor) to gain the input. You may build similar circuit for your stereo sound system.

schematic diagram:

This easy circuit provides good gain to weak audio signals such as electret microphone. Use it in front of an RF oscillator to make an RF transmitter that’s very sensitive to sound.

2×22W Stereo Car Audio Amplifier schematic diagram

This is a schematic diagram of stereo audio amplifier for your car. The circuit is powered by a single IC TDA1553 with some external components, this IC will handle your stereo car audio system.

The TDA1553CQ is a monolithic integrated class-B output amplifier in a 13-lead plastic DIL-bent-SIL power package. It contains 2×22 W amplifiers in BTL configuration. The device is primarily developed for car radio applications.

The TDA1553CQ contains two identical amplifiers with differential input stages and can be used for bridge applications. The gain of each amplifier is fixed at 26 dB.

Special features of the device are:

3-state mode switch
· standby: low supply current (<100>

Loudspeaker protection
When a short-circuit to ground occurs, which forces a DC voltage across the loudspeaker of >= V, a built-in protection circuit becomes active and limits the DC voltage across the loudspeaker to <= V. Pin 12 detects the status of the protection circuit (e.g. for diagnostic purposes).

Short-circuit protection
If any output is short-circuited to ground during the standby mode, it becomes impossible to switch the circuit to the mute or operating condition. In this event the supply current will be limited to a few milliamps.

Download the TDA1553CQ datasheet

25W Power Amplifier based IC LM1875

Short circuit protection, 94dB supply rejection ratio, thermal protection, S/N ratio in excess of 100dB, Open loop gain typically 90dB and 70mA quiescent current, LM1875 is great enough to give you good audio performmance. This power IC will amplify the audio signal up to 30W output power.

Component part list

R1 _____________ 1K R2 _____________ 1M R3 _____________ 22K R4 _____________ 10K R5 _____________ 180K R6 _____________ 1R IC1 ____________ LM1875

C1 _____________ 1uF 50V C2,6 ___________ 100nF C3 _____________ 22uF 63V C4 _____________ 0.22uF C7,5 ___________ 220uF 50V Miscellaneous: Fuse holder & cover 2 amp fuses

Visit this 25W Power Amplifier page for detail explanation

Simple Gate Alarm

Here the simple gate alarm circuit that built based on CMOS IC 4093B. With CMOS IC, this circuit must be work with small universal power supply.

IC1a is a fast oscillator, and IC1b a slow oscillator, which are combined through IC1c to emit a high pip-pip-pip warning sound when a gate (or window, etc.) is opened. The circuit is intended not so much to sound like a siren or warning device, but rather to give the impression: "You have been noticed." R1 and D1 may be omitted, and the value of R2 perhaps reduced, to make the Gate Alarm sound more like a warning device. VR1 adjusts the frequency of the sound emitted.

IC1d is a timer which causes the Gate Alarm to emit some 20 to 30 further pips after the gate has been closed again, before it falls silent, as if to say: "I'm more clever than a simple on-off device." Piezo disk S1 may be replaced with a LED if desired, the LED being wired in series with a 1K resistor.

Figure 2 shows how an ordinary reed switch may be converted to close (a "normally closed" switch) when the gate is opened. A continuity tester makes the work easy. Note that many reed switches are delicate, and therefore wires which are soldered to the reed switch should not be flexed at all near the switch. Other types of switches, such as microswitches, may also be used.

Spurce: http://www.zen22142.zen.co.uk/Circuits/Alarm/Galarm.html