# Help a Dummy - momentary switch circuit design

#### george-harris2021@outlook

Joined Aug 6, 2023
4
I'm almost completely without knowledge when it comes to designing circuits although I'm getting good at soldering them together. I need some (lots of) help designing a momentary switch circuit design to replace the slide switch in the attached circuit. I've read some post that suggest a latching circuit is what I need. Unfortunately what I have seen have been too big and bulky for what I need. I need help in designing something that uses the smallest possible components and fits is the smallest area.

Right now, with the slid switch, the entire circuit fits on a board that measures a half inch by half inch, excluding the battery and motor. The power source is a 2 to 5 volt battery and the brushed motor draws around half an amp. The switch is on the enable pin of a LDO regulator

Any, and all, help in circuit design and/or component selection would be appreciated.
Also, let me know if I should post my help request on a different forum.

George

#### sghioto

Joined Dec 31, 2017
5,140
What is the output voltage of the regulator.
I can think of a surface mount 555 chip for the latch but would need a dual sided pc board if the size is restricted to 1/2 inch square.

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#### george-harris2021@outlook

Joined Aug 6, 2023
4
What is the output voltage of the regulator.
I can think of a surface mount 555 chip for the latch but would need a dual sided pc board if the size is restricted to 1/2 inch square.
Output voltage of the regulator is 2 to 3.5 volts. Output dependent on battery voltage and trim pot setting.

Dual sided PCB is acceptable but not desirable. Can you explain, maybe with a circuit sketch, how you would use a 555 as a latch. I'm trying to stay away from anything that needs programming.

#### AnalogKid

Joined Aug 1, 2013
10,797
I don't understand the question. Are you asking for a recommendation of a different type of switch, such as a simple momentary switch? Or maybe a latching pushbutton switch, called an alternate-action switch? For this type, you press once and the switch latches itself with the contacts closed. When you press the button again, the switch latches itself with the contacts open.

OR - are you asking about a circuit that effectively turns a simple momentary pushbutton switch into an alternate action switch with a circuit called a toggle flipflop?

ak

#### george-harris2021@outlook

Joined Aug 6, 2023
4
I don't understand the question. Are you asking for a recommendation of a different type of switch, such as a simple momentary switch? Or maybe a latching pushbutton switch, called an alternate-action switch? For this type, you press once and the switch latches itself with the contacts closed. When you press the button again, the switch latches itself with the contacts open.

OR - are you asking about a circuit that effectively turns a simple momentary pushbutton switch into an alternate action switch with a circuit called a toggle flipflop?

ak
I think that I'm asking for the second one. I want to replace the present slide switch with something that is smaller and lighter. I think, or at least hope, that a momentary contact switch can be made to work, push to turn on. There is no 'off ' function needed, the motor runs until the battery is depleted. Maybe just to 'on' side of a flip flop circuit would work.

The latching pushbutton switches that I have seen have been way too big and heavy.

#### sghioto

Joined Dec 31, 2017
5,140

#### george-harris2021@outlook

Joined Aug 6, 2023
4
Outstanding sghioto!! That looks like the way to go. Now I've got a starting point. I will let you critique what I come up with.

Thanks so much. To everybody that responded.

#### Ya’akov

Joined Jan 27, 2019
8,568
I'm almost completely without knowledge when it comes to designing circuits
Welcome to AAC. Glad to have you with us.

Just an aside: you are not a "dummy". There is a difference between ignorance and stupidity. The former is easily rectified by learning, the latter is a permanent condition that is untreatable.

This is a longstanding complaint of mine. People who are otherwise very accomplished, and have shown the ability to learn and apply technical topics suddenly call themselves "dummies" because they haven't yet learned some new one. It's laudable to be aware of one's ignorance but to leap from that to confession of stupidity really rankles.

Back when I was writing books on computer topics, the "for dummies" book series really rubbed me the wrong way. In fact I was working on a project with a large publisher that was to be a series called "Making Technology Work". The premise was that smart but ignorant people would be able to get high quality, high accuracy information with multiples levels of detail based on the use of what amounted to printed hypertext.

In any case, I always said that if I was consulting with my brain surgeon and noticed the book "Windows for Dummies" on her desk, I would be looking for a second opinion as soon as I left.

We now return you to our regularly scheduled programming, already in progress...

#### AnalogKid

Joined Aug 1, 2013
10,797
push to turn on. There is no 'off ' function needed,
As you can see in the responses, that information changed everything. This is a common request, and there are lotsa ways to solve it.

Often in these forums, getting the question right is harder than the answer.

ak

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