Persistant circuit with a tactile switch

[RhysGM]

Hello,

I have a set of switches that would look good on my project however they are all tactile SPST. Is there anyway (without the use of an IC) to turn these momentary switches into a SPDT and/or a latching SPST.

I want to switch the circuit on and off with a green and red led changing colour depending on the state and also switch a set of lights on and off.

It would also be good if they remembered their state when the entire circuit is switched off.

Thanks for any advice.
Rhys

 

[berkeman]

Hello,

I have a set of switches that would look good on my project however they are all tactile SPST. Is there anyway (without the use of an IC) to turn these momentary switches into a SPDT and/or a latching SPST.

I want to switch the circuit on and off with a green and red led changing colour depending on the state and also switch a set of lights on and off.

It would also be good if they remembered their state when the entire circuit is switched off.

Thanks for any advice.
Rhys

It doesn't sound like you can do what you want. What's wrong with using some simple flip-flops (FFs)? Or else look at switch manufacturer websites until you find a style of latching switch that you like...

 

[justsomeguy]

I wouldn't say you can't do it, but the circuit is going to get very complicated very fast, compared with just slapping some ICs down. A slow clock and a T-flipflop will do what you want to a degree: The output will change states as long as the button is held down, and hold whatever state it has when released, so you'd want the clock no faster than 1-2Hz or it'll toggle too fast for you to accurately let go in time.

If you use the switch to trigger a oneshot, the oneshot can then act as the trigger to the flipflop.

Without using ICs you're talking about at least a dozen different parts required to build this circuit, and you need to build it for each button.

 

[Averagesupernova]

Use a mechanical latching relay. The kind with 2 coils. Arrange the contacts so that each time the switch is pushed it activates the coil that will change the contact position. Use a cap in series so it doesn't chase its tail.

 

[alphysicist]

Hello Rhys,

Thank you for reaching out with your question about switches and circuit design. I can offer some suggestions and solutions to help you achieve your desired circuit.

First, let's discuss the difference between a SPST (single-pole, single-throw) and a SPDT (single-pole, double-throw) switch. A SPST switch has only two positions - on and off. A SPDT switch has three positions - on, off, and a middle position where the circuit is connected to a different output. So, to convert a tactile SPST switch into a SPDT switch, you would need to add another output to the switch.

One way to do this without using an IC (integrated circuit) is to use a relay. A relay is an electrically operated switch that can be used to control a larger current using a smaller current. You can connect your tactile switch to the relay's coil and use the relay's contacts as your SPDT switch. This would allow you to switch between the green and red LED and also control the set of lights. Additionally, you can use a latching relay to keep the circuit in its last state even when the power is turned off.

Another option is to use a transistor to create a "flip-flop" circuit. A flip-flop is a digital circuit that can store a binary state (on or off) and can be used to create a latching switch. By connecting a tactile switch to the transistor's base, you can control the flow of current through the transistor and switch your circuit on and off. This method would also allow you to use a single tactile switch for both the LEDs and the lights, as the flip-flop circuit can store two different states.

In both of these solutions, it is important to make sure that the relay or transistor can handle the current and voltage of your circuit. You may need to use additional components, such as resistors, to protect these components and ensure they function properly.

I hope this information helps you achieve your desired circuit design. As always, it is important to carefully test and troubleshoot any circuit before using it in a final project. Good luck with your project!

Best,