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Here is a 12 volt / 2 amp lamp dimmer that can be used to dim a standard 25 watt automobile brake or backup bulb by controlling the duty cycle of a astable 555 timer oscillator. When the wiper of the potentiometer is at the uppermost position, the capacitor will charge quickly through both 1K resistors and the diode, producing a short positive interval and long negative interval which dims the lamp to near darkness.... [read more]

Commercially available hearing aids are quite costly. Here is an inexpensive hearing aid circuit that uses just four transistors and a few passive components.... [read more]

These goals were achieved by using a discrete-components op-amp driving a BJT complementary common-emitter output stage into Class B operation. In this way, for small output currents, the output transistors are turned off, and the op-amp provides all of the output current. At higher output currents, the power transistors conduct, and the contribution of the op-amp is limited to approximately 0.7/R11. The quiescent current of the op-amp biases the external transistors, and hence greatly reduces the range of crossover.... [read more]

Do you long for a beach holiday on a tropical island, but you don’t have the necessary wherewithal? We’ve got just the answer: build the i-TRIXX surf simulator, put on your headphones, and dream yourself away from this dreary realm. Let the rhythmic rush of the waves transport you to a sun-drenched beach with gently swaying palm trees, and relax for a while before returning to a chilly confrontation with reality. That’s the ultimate in low-budget travel.... [read more]

This is a classic divider of frequency via two. It is achieved with a classic circuit T-flipFlop, round IC1 [ 4011 ]. In the circuit, the frequency of network, after are limit the negative half-s period of sine wave and transform in square wave, are divided via two. Thus for frequency50 HZ, we will take in the exit pulse of frequency 25 HZ. The supply of circuit it is + 5V and does not need high benefit in current.... [read more]

Designed around the popular ZN414 ic this receiver covers the AM band from 550 - 1600 KHz with the values shown. For Longwave the coil needs to be changed. Use one from an old MW radio to save time. The ZN414 is a tuned radio frequency designed and incorporates several RF stages and an AM detector. It is easily overloaded and the operating voltage is critical to achieve good results.... [read more]