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Momentary switch and LED?

Thread starter #1
Hi
I have a momentary push button switch and wanna be able to turn a LED On and Off with it.
I need the simpliest possible solution for this, and the cheapest.
From what i understand flip flop circuits can do the trick but my knowledge in especially building from diagrams are very limited.
It must be 5VDC as well. Can someone put me in the right direction and maybe give me a full list of parts needed along with a good explanation or even better some paint type of scheme for the wiring it would mean the world to me.
For a jk flip flop would this work? 4027B SOIC Dual J-K Master-Slave Flip-Flop
Thanks in advance!
//Jimmie
 
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alec_t

Well-Known Member
Most Helpful Member
#5
This will do it :-
Toggle.gif
 
Thread starter #6
here we go :(
i cannot read or understand wiring diagrams..
only way i can get something like this togheter is to get a complete list of parts needed including like a paint-like drawing of how it need to be wired haha.
thanks anyway!
 

alec_t

Well-Known Member
Most Helpful Member
#7
Ok then, here's a drawing :-
Toggler.gif

....and here's the recipe :-

Ingredients
1 x 5V supply
1 x 14-pin DIL socket
1 x momentary action switch
1 x 74HC14
1 each of 100kΩ, 3.3kΩ and 220Ω resistors (1/4 watt or less)
1 x 100nF (= 0.1 uF) capacitor (polyester)
1 x LED
Hook-up wire

Method
Familiarise yourself with anti-static precautions needed for handling CMOS circuits.
Note that there is a notch or other mark at one end of the 74HC14 chip to help identify pin 1.
Observe the correct polarity of the 5V supply and the LED (the LED cathode is usually shorter than the anode lead, or there is a flattened section of the LED body nearest to the cathode, or the 'cup' inside the LED is usually the cathode).
Leaving the chip to last, wire the DIL socket to the other components as shown, then insert the chip.
Note: depending on the LED you use it may be necessary to change the 220Ω resistor to one with a value in the range 100-560Ω to give a suitable brightness.

Happy cooking!
 
#8
This looks ideal for I want to do aswell. I will be using a 9V battery, What would I need to change on the above diagram to get that working?

Thanks for any input. Greatly Appreciated.
 

Mr RB

Well-Known Member
#10
This is not eaxctly what you asked, but you can get push on/push off type button switches that look just like the momentary button switch.

That's all you need, job done, no messing about.
 

alec_t

Well-Known Member
Most Helpful Member
#11
9V is too high for a 74HC14 , which is why a CD40106 is suggested in post #9. However, that IC can't handle as much current to drive the LED so you would need to increase the 220 Ohm resistor to ~ 1000 Ohm (assuming a typical red LED is used) and be satisfied with reduced brightness. But Mr RB's suggestion would be a simpler solution!
 
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#13
Hi there

Firstly I wanted to establish some information about your switch. So when you press your switch this briefly makes contact then is broken when in the pressed position, when your release the button does it make momentry contact again when being released or does it only make momentry contact when being pressed?
 

alec_t

Well-Known Member
Most Helpful Member
#15
So is this componenet essentially a direct replacement for the 74HC14?
Only in the sense that its pin connections are the same. It is a CMOS IC so you should take the usual ant-static precautions when handling it. A
will I only need to replace the resistor which connects to the LED?
Try 1kΩ for the resistor. Even with that the IC will struggle and its output pin voltage will drop and drive < 7mA through the LED. You could connect gates within the IC in parallel to boost the drive current. The inputs of any unused gates of the IC should be grounded to prevent circuit instability.
 
#16
Thanks Alec.

I am looking to use this circuit to turn my reverb on and off on my desk which currently uses a Momentary switch, currently when the button is pressed on my non LED cheapo switch it shorts the 1/4 input jack to the desk and turns the reverb on/off etc.

Taking this diagram into account, If when the button is pressed I wanted to not only turn the LED light on but also send a signal back to the desk, where would I wire in a 1/4 input jack to the circuit to make that short. Would it be as simple as adding the + and - of the jack via 2 wires to momentary switch's points. I hope that makes sense. I am new to electronics but have been reading loads trying to gain a knowledge of this kind of thing so sorry if I am off bounds.
 

alec_t

Well-Known Member
Most Helpful Member
#17
If shorting the jack input to ground, as you seem to be doing at the moment, doesn't harm the reverb then the following circuit (adapted from the earlier one) should do the job. The transistor switches on when the LED switches on, and its collector is pulled down to ground. The transistor can sink > 10mA, which is probably sufficient.
 
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#18
Cheers for that, that makes sense. can I be extremely cheeky and ask you to modify the toggler drawing, the one that shows the wiring (with the input jack part) I have not grasped circuit diagrams fully yet. Your help is appreciated and are more than willing to buy you a few pints for your troubles. Regards
 

alec_t

Well-Known Member
Most Helpful Member
#19
the toggler drawing, the one that shows the wiring (with the input jack part)
:confused: What number post is that shown in?
 

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