Random circuits

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Intercommunication (Intercom)

This is a great intercom circuit that can be used in many ways. It uses 22V to operate and maybe it will work at a lower voltage (you can try it). For input/output it uses a loundspeaker (20-45 Ohm) on each side.... [read more]

Power Amplifier 8W

Although the TDA2030 can deliver 20 watts of output power, I deliberately reduced the output power to about 8 watts to supply 10 watt speakers. Input sensitivity is 200mV. Higher input levels naturally will give greater output, but no distortion should be heard.... [read more]

Repeating Interval Timer

This circuit has an adjustable output timer that will re-trigger at regular intervals. The output period can be anything from a fraction of a second to half-an-hour or more - and it can be made to recur at regular intervals of anything from seconds to days and beyond.... [read more]

Doorbell for the Deaf

This circuit provides a delayed visual indication when a door bell switch is pressed. In addition, a DPDT switch can be moved from within the house which will light a lamp in the door bell switch. The lamp can illuminate the words "Please Wait" for anyone with walking difficulties.... [read more]

Courtesy Light

This circuit is intended to let the user turn off a lamp by means of a switch placed far from bed, allowing him enough time to lie down before the lamp really switches off. Obviously, users will be able to find different applications for this circuit in order to suit their needs.... [read more]

Headphone amplifier with TDA2004

A opamp. medium power, here it‘s used as amplifier of headphones with possibility drive low loads. It contains in a nutshell two amplifiers.... [read more]