Circuit Diagrams Blog

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Model Railway Turnout Control

This small circuit can be used to control model railway turnouts operated by AC voltages. A logic level in the range of 5–12 V can be used as the control signal. The coils of the turnout are switched using triacs. Changes in the logic level of the input signal are passed on […]

May 28th, 2015|Health and Hobby|0 Comments

Flickering Light II

Regardless of whether you want to effectively imitate a house fire, a campfire, or light from welding, the circuit described here fills the bill without using a microcontroller, although it does use a larger number of components (including some truly uncommon ones). The circuit is based on three oscillators, which are […]

May 27th, 2015|Lights and Leds|0 Comments

A Very Useful Timed Beeper Circuit Schematic

Beeps 7.5 seconds after a preset time, Adjustable time settings: 15s. 30s. 1min. & othersThis circuit is intended for alerting purposes after a certain time is elapsed. It is suitable for table games requiring a fixed time to answer a question, or to move a piece etc. In this view it is […]

May 27th, 2015|Clock and Timers|0 Comments

Thermal Fan Controller By IC 741

The controller uses one or more ordinary silicon diodes as a sensor, and uses a cheap opamp as the amplifier. I designed this circuit to use 12V computer fans, as these are now very easy to get cheaply. These fans typically draw about 200mA when running, so a small power transistor […]

May 26th, 2015|Home and Garden|0 Comments

Room Recorder

My wife was working on a doctoral dissertation and needed to do some field work involving personal interviews in various settings. What would be the best way, technically speaking, to record the interviews? To pass a tape recorder or microphone back and forth seemed too awkward and clipping wired microphones to […]

May 26th, 2015|Microphone|0 Comments