Electronic C

Speech Pitch Controller using MSM6322GSK

That circuit uses the MSM6322GSK which is only available in small 24 pin plastic SOP style package. A speech pitch converter IC that operates in real time and requires very few external components. It has a microphone preamplifier and line level input and the output requires only a single transistor to directly drive a loudspeaker. […]

Digital Volume Control by DS1669

This circuit could be used for replacing your manual volume control in a stereo amplifier. In this circuit, push-to-on switch S1 controls the forward (volume increase) operation of both channels while a similar switch S2 controls reverse (volume decrease) operation of both channels. A readily available IC from Dallas semiconductor, DS1669 is used here. Read […]

IR Headset using transistor BC549

Here is a simple IR headphone circuit that is suitable for listening to TV or radio with out disturbing others.For beginners the IR headset is a better option than FM head sets because they often produce desirable sound quality with out tuning as well as difficult impedance matching that is often done in radio circuits […]

Water activated musical bell using M3482

This is a simple musical alarm circuit which produces a musical tone when water or some conducting liquid comes in contact with the two sensor wires provided. The circuit is based on four transistors and one melody generator IC (M 3482). When water comes in contact with the sensors wires A & B, the base […]

Transistor intercom circuit

Here is a simple but effective intercom circuit that is based fully on transistors.The circuit is based on a three stage RC coupled amplifier. When the pushbutton S2 is pressed, the amplifier circuit wired around T1 & T2 becomes an astable multivibrator and starts producing the ringing signals. These ringing signals will be amplified by […]

Sound Switch Control with BC182B

Notes: This sensitive sound operated switch can be used with a dynamic microphone insert as above, or be used with an electret (ECM) microphone. If an ECM is used then R1 (shown dotted) will need to be included. A suitable value would be between 2.2k and 10kohms. The two BC109C transitors form an audio preamp, […]

Simple Thermocouple Amplifier by OP07

The OP07 is in a non inverting amplifier so as not load the mV of thermocouple, the zeners are to protect circuit if junction contacts heaters or the earth gets broken. The RC is to filter out 50Hz pick up in thermocouple wires if near heater wiring and also reduces reading jumps when high current […]

Backup Lamp light fails by Vmos

There are a few situations when a power failure is particularly difficult to handle. Some of these circumstances occur in the bathroom. This little circuit will pay for itself many times over the first time it is used, especially if you are in the shower. Read more original source: http://www.techlib.com/files/backup.pdf

Automatic Solar Power Supply Circuit

The circuit can be made automatic by adding a 1k resistor and diode: The oscillator will turn off when the output from the solar panel is above 1.3v and although the circuit does not shut down to zero current, it consumes about 3 mA, while the shut-off circuit takes about 1mA. On a bright day, […]