Need Help with Push Button Membrane pad on circuit

Using Arduino General Electronics
1

I have a Push Button membrane pad for my paintball gun. The problem is that the push button only stays on when you hold the button down. Once you let off, the power is cut. I need a small device (like a relay) that will keep the circuit on after I let off the button, when I press the button again the circuit will shut off. If that make sense, I'm bad at explaining things. The voltage across the switch is 7.5 volts

help me please, thanks

2

I assume that since you posted on the Arduino forum, that you are using an Arduino. If so, then you'd could do that entire through the code. If you can give us a little more detail on exactly what you are doing, we'll be able to help you more.

3

I'm wiring without an arduino right now. Its for my old wire harness. I wanted to use a push button membrane pad instead of the on off switch. I am coding an arduino to drop in my gun eventually but I want to go play paintball soon and the arduino programming is going to take me longer than wiring a small part to get the push button to work.

4

There are switches, "push on, push off" that you may be able to use.

5

I was thinking more of like a latching relay that will maintain power through the circuit until I press the membrane pad again then relay will unlatch and cut the power. My professor also told me a flip flop switch might work.

6

If you ever go to a place like mouser.com, digikey.com, jameco.com, element14.com, etc. you will find the choice of buttons to be quite extensive. Here are some push and hold buttons that fit in breadboards, that I have on my ebay watch list: http://www.ebay.com/itm/151097579681?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

Adafruit has some 16mm illuminated switches that are latching, and since it has a LED inside, you can turn the LED on when the circuit is active: 16mm Illuminated Pushbutton - White Latching On/Off Switch : ID 1478 : $1.95 : Adafruit Industries, Unique & fun DIY electronics and kits

I also noticed Adafruit has this tactile on/off switch, which is a lot smaller than the other: http://www.adafruit.com/products/1092
7

I'm using this membrane pad because its made for paintball guns, fits well on my marker and looks nice. If I wanted to use the regular on/off switch I would but that's boring and I want to try and mod my gun to use this membrane pad. I have heard that latching relays could work, flip flop devices, ect. I need something that is small and can fit in a tight space within my paintball gun's grip frame.
I need some input that can help me with this problem

IMG_0478.JPG
IMG_0478.JPG3240×4320 2.95 MB

8

I need a small device (like a relay) that will keep the circuit on after I let off the button, when I press the button again the circuit will shut off.

Use a 74LS74 dual flip flop, ( you only need one ) Connect the Q bar output to the D input, connect your switch between the clock input and ground, put a 4K7 pull up on the clock input as well. The Q output will then toggle with the button pushes.

9

thanks, I sent you a pm as well for more details on the wiring info

10

For in case Mike's inbox is flooding: google datasheet 7474 or find it through wikipedia:

http://www.nxp.com/documents/data_sheet/74HC_HCT74.pdf

This will result in something like this (dont mind that ít's not dip form, pinout is the same):

So Mike suggests:
pin 6 to pin 2
pin 3 to switch to gnd
pin 3 with 4k7 to Vcc
pin 7 to gnd
pin 14 to Vcc

However, you might need to insert a small circuit to get rid of contact bounce, it depends on your trigger. Contact bounce is where you trigger will give a few spikes between low and high voltage before it actually stays switched: this would switch your tagger on and off repeatedly. A debouncing circuit could look like this:

For the schmitt inverter you can use 7414. Or combine all in one go and build a push on, hold off switch with 7413 (schmitt nand gates):

709×346 48.9 KB

On the right side is whatever electronic switch (transistor, mosfet) you want to use to switch on your marker.

11

You shouldn't use PMs for technical questions because it hides information from people trying to follow this thread. You said:-

Thanks for giving me good advice, I have some questions though. I want to make sure these are the right pieces to buy before I order. Ill use mouser or digikey, here is what I came up with after directly searching what you suggested.
flip flop--> http://www.mouser.com/ProductDetail/Texas-Instruments/SN74LS74AN/?qs=sGAEpiMZZMvxP%252bvr8KwMwB25p6a2AxEEGyZpKqrZ5lw%3D

4K7 pull up-->http://www.mouser.com/ProductDetail/Honeywell/SD5630-002/?qs=sGAEpiMZZMtdU8v%2FCHkq3yi6miC7Q52Q <--I dont understand what this does,can you explain this part a little more.

How will I wire everything up? I have the positive wire from my battery cut and that is wired to my old on/off switch. My membrane pad works just like the on off switch except for the fact that it cuts power as soon as the button is released

Yes I think you have bittern off more than you can chew here if you are asking if a link to a 4K7 pull up resistor is the right thing.

What we need to know is what voltage you get from your gun and what current does this switch control. Without this it is impossible to design anything for you. The 74LS74 needs to be fed with 5V, so if you don't have that then you either need to generate it or get another chip that will handle what you have.
The output of a chip like this is only good for 20mA or so, if your gun takes any more then you will need an output buffer, a transistor or FET is normal. However id you want to interrupt the positive supply as opposed to ground then you need what is called a top switch.

12

Thanks for the great advice, yes I do need to provide some Information, I said already the voltage is 7-8 volts dc. The current I believe is 14.87 mA so 0.0148 amps. Here is a picture so a professional can confirm I'm reading this correctly. The positive wire is cut for the original on off switch. I'm assuming I need to use that to power the flip flop. I'll wire one end to the Vcc input and the other end to the Q output?

IMG_0483[1].JPG

13

CaptinJack, on the right side of your diagram I would connect one end of my switch to the Vout and the other side to ground? since the CD4011BPWR is rated with a max voltage of 18v then I'm fine running 7-8 volts right?

14

Sheesh. Does everything have to be at 8 MegaPixels?

15

Sheesh. Does everything have to be at 8 MegaPixels?

You and I agree in this.

There needs to be some guidelines about this.

  1. Crop your picture If what you are showing is only 10% of the image, crop the image to only show that 10%
  2. if the image is larger than 1200 x 1200 Pixels, shrink it. Trying to scroll around a larger image is difficult and wastes time... remember... the people who actually look at it are trying to help... don't make them upset.