circuit



Temperature Monitoring circuit

Circuit : Andy Collinson Email me Description: A simple op-amp circuit that will trigger a relay when a preset temperature is reached. Please note that there is no hysteresis in this circuit, so that if the temperature changes rapidly, then the relay may switch rapidly. Description This circuit uses an ordinary NTC thermistor with a […]


Gas Tube Quench Circuit

It seems to be common knowledge that a NE-2 or similar neon lamp can be pressed into service as radiation (x-ray) detector. But can a simple lamp serve as a low-level detector, possibly replacing a Geiger tube?  Initial experiments with a variable voltage source and a NE-2 in a relaxation circuit consisting of a series […]


Neon Quench Circuit

Gas Tube Quench Circuit (also see Neon Bulb as Resistor) It seems to be common knowledge that a NE-2 or similar neon lamp can be pressed into service as radiation (x-ray) detector. But can a simple lamp serve as a low-level detector, possibly replacing a Geiger tube?  Initial experiments with a variable voltage source and […]


Sine Wave Generator with 1KHz Frequency

Part List Circuit Project Description This simple circuit has been designed to generate sine waves with a frequency of 1 KHz while featuring low distortion and low output impedance until 1 V RMS as it obtains power from batteries. Terminology Sine Wave – a smoothly varying wave that repeats itself which can be thought of […]


Fade-In & Fade-Out Effects to the In-Car Lights

Description This circuit adds a nice fade-in fade-out visual effects when switching your in-car lights on and off. The fading time can be changed by adjusting the charging and discharging times of the capacitor.  To do this, adjust the values of the 10 KOhm and 4.7 MOhm resistors. BUZ74 is a SIPMOS power transistor (Siemens […]


Ultrasonic Burglar Alarm

Description Ultrasonic Burglar Alarm: Transmitter and receiver parts of the circuit are connected each other by using a triple cable. System operates with 20V supply and 10V effective output voltage drives the ultrasonic transducer at its highest value. Transmitter circuit gives the maximum gain at 40kHz.  Ultrasonic transducers in the circuit must be placed vis-à-vis […]


500Hz Modulated Ultrasonic Transmitter

Description Ultrasonic oscillations which are generated by unmodulated ultrasonic transmitters commonly for remote control are usually affected from other ultrasonic sources in the media and that’s why we are giving a 500Hz modulated ultrasonic transmitter circuit here. Voltage supply of the circuit is 9 Volts and any change of the value will change the frequency […]


Programmable Current Source by LM317

Description Accurate and stable current supplies are generally needed in electronic labs especially for creating V-I curves, charging and discharging batteries, preloading power supplies and for many other purposes and applications. This circuit provides a current supply that can be programmed by using three digit BCD switches that allows us to set the current from […]


Simple Telephone Security Device

Description In the market, there are several types of telephone security devices which are generally simple but not cheap. On the other hand most of them do not guarantee protection against unauthorised operation. Generally they provide blinking or beeping type line-top/misuse indications. This circuit continuously checks the tel. lines and when it detects a misuse, […]