Rongge

A photodiode Dl feeds high gain IR remote control preamp 1C, a CA3237E. U2 is a PLL FM detector tuned to around 100 kHz. The detector output is amplified by U3 and it can drive a speaker or a set of headphones. Wireless IR Headphone Receiver Circuit Schematic

Quality Stereo Wireless Microphone or Audio . This stereo FM wireless microphone also makes a great quality audio link. We tested it to beyond 50 meters and it was rock solid. It’s certainly not the first wireless microphone we’ve ever published but this one is a little different. It’s stereo, providing surprisingly good quality sound. Second, it has a really good range. We tested it at well over 50m and it was still performing very well – noise-free, in fact – but at the time we couldn’t get our receiver any further away. So it’s likely to have even better range than that. Complete Project: It's easy to build, requires very little setup... and it's cheap! In fact, the low price might turn some people off, thinking it's low quality. Try it - and be pleasantly surprised! Third, it really is simple to build – the hard work (the transmitter module) is already done for you. It’s just a matter of assembling the microphone module, which contains the electret mics themselves, ...

Small and simple circuit, Suitable for home appliances Normally home appliances are controlled by means of switches, sensors, etc. However, physical contact with switches may be dangerous if there is any shorting. The circuit described here requires no physical contact for operating the appliance. You just need to move your hand between the infrared LED (D2) and the phototransistor (Q1). The infrared rays transmitted by D2 is detected by the phototransistor to activate the hidden lock, flush system, hand dryer or else. This circuit is very stable and sensitive compared to other AC appliance control circuits. It is simple, compact and cheap. Current consumption is low in milliamperes. The circuit is built around an IC CA3140, D2, phototransistor and other discrete components. Circuit Diagram: Parts: R1 = 470R R2 = 100K R3 = 3.3K R4 = 10K D1 = 1N4007 D2 = IR LED Q1 = L14F1 RL = 5Vdc Relay IC = CA3140 Q2 = BC548 Circuit Operation: When regulated 5V is connected to the circuit, D2 emits i...