This would be done in 12V and the sequence will be initiated by a manual switch. "I am looking to build a circuit that would control an output relay. The following circuit was requested by Fastshack3 Delay Timer with Relay
This circuit was requested by one of the avid readers of this blog, Mr.Marco.Ī simple delay OFF alarm circuit is shown in the following diagram. The above circuit can be modified to produce a two step sequential delay generator. The solution to the above problem is provided in the following schematic: Two Step Sequential Timer Is there any way to take a long pulse into a circuit and send a much shorter pulse out? I have a situation where I have a pulse of 12V that lasts about 4 seconds (from a rotary switch being turned by a slow motor) but I only want about half a second pulse (to trigger a mechanical bell/chime).
Glen (one of the dedicated readers of this blog): The following circuit shows how the associated push button may be rendered inactive as soon as it's pressed and while the delay timer is in the activated state.ĭuring this time any further pressing of the push button has no impact on the timer as long as the output is active or until the timer has finished its delay operation. The above delay OFF effect without a push button can be further improved by using two NPN transistor, and by using the capacitor across base/ground of the left NPN If the above design is intended to be used without a push button, the same may be implemented as indicated in the following diagram: On releasing the push button, though the power to the base gets disconnected, the transistor continues to conduct with the aid of the stored energy in the capacitor which now starts discharging its stored charge via the transistor. However in the course of the above action, the capacitor also gets charged fully. On depressing the button momentarily, a positive voltage from the supply line enters the base resistor and switches ON the transistor and subsequently the LED. The transistor has been provided with the usual base resistor for the current limiting functions.Ī LED which is used here just indication purposes behaves like the collector load of the circuit.Ī capacitor, which is the crucial part of the circuit gets the specific position in the circuit, we can see that it's been placed at the other end of the base resistor and not directly to the base of the transistor.Ī push button is used to initiate the circuit. The first circuit diagram shows how a transistors and a few other passive components may be connected for acquiring the intended delay timing outputs. Using a Single Transistor and Push Button You may also want to read about IC 555 based delay timers. Let's analyze the various configurations in details. Without the specified delay the circuit could malfunction or even get damaged. In many electronic circuit applications a delay of a few seconds or minutes becomes a crucial requirement for ensuring correct operation of the circuit.
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