Any IC geeks out there?

magicmike · Post by **magicmike** » Thu Sep 04, 2003 7:56 pm

I need a simple circuit to use with a push button switch. Basically I need something that will have no output at rest, a single output when a momentary switch is pressed once, two seperate outputs when the switch is pressed again, and both outputs off when the switch is pressed again. I need it to be 12Vbut can be 500ma (I can use relays off of the circuit) Can anyone help me out

P.S. I'm kidding about the geek thing

Any help would be great, Thanks in advance,

Mike

ciper · Post by **ciper** » Thu Sep 04, 2003 8:24 pm

How about a rotory switch with three positions? Similar to a printer port switch box with less connections.

magicmike · Post by **magicmike** » Thu Sep 04, 2003 11:27 pm

no, I need something that can take a negative pulse so I can use an exsisting switch as the push button.

vrg3 · Post by **vrg3** » Thu Sep 04, 2003 11:52 pm

A rotary switch would certainly be the easiest way to go, but they can be hard to find...

Let me make sure I understand -- you want a device connected to +12v and ground, and with a pushbutton on it, and two output wires coming out of it, right? And pressing the button would switch from both outputs being floating (disconnected), to output 1 having +12v on it, to both outputs having +12v, and back to both of them being off?

Off the top of my head, I think you could do that with a 4017; it's a decade counter with decoded outputs. You'd basically leave the 0 output alone, use the 1 output to turn on the first relay, use the 2 output to turn on both relays, and use the 3 output to reset the counter.

Something maybe like this (pardon the artwork; it's a humungous pain to draw circuits in MS Paint on a computer the size of a video tape):

http://www.graphics.cornell.edu/~v/pics ... ircuit.gif

vrg3 · Post by **vrg3** » Thu Sep 04, 2003 11:53 pm

Heh, you posted while I was writing, but the design I gave uses a negative pulse (the push button pulls the input to ground).

magicmike · Post by **magicmike** » Fri Sep 05, 2003 12:43 am

Thank you so much, that is exactly what I need. I just need to know what that resistor value would be. I dont need 12volts for anything I'm doing but I figured the circuit would need some possotive voltage to work somehow. If it does then it would be 12volts.

Thanks again,

Mike

vrg3 · Post by **vrg3** » Fri Sep 05, 2003 2:40 am

Maybe you should tell us a little more about what you're trying to achieve and what your previous experience with building electronic circuits is...

That diagram I posted above is just a general outline... You'd of course need the actually do something with the two relays. I accidentally labeled the main IC "4016" instead of "4017." Oops. :)

In any case, about 2 kiloohms should do for all three resistors. Don't forget to bypass the power supply (on both sides of the 7805), too.

Basically, make sure you understand how the thing is supposed to work; don't just build it blindly, since I haven't tested it or given it too much thought.

magicmike · Post by **magicmike** » Fri Sep 05, 2003 4:26 am

Well I am a car stereo guru so I am always trying to do something "trick". I just got my Infititi with the BOSE system so I didn't want to change the whole system out, I was just planning on adding some subs. I have quite a few amps kicking around as well as speakers so I was going to put two 12"s with one soundstream ref. 500 on each sub. The reason for the switch is that I want a cool way of selecting one amp on for just one 12 to play, 2 amps on for both subs to play and no subs if I chose. I was planning on using the BOSE factory cassette eject switch to accomplish this. I thought it would be cool and I'd add some led's somewhere also so I could visually see whats on. Perhaps a bi color like green for one amp red for two and off for off. I know you mentioned a mechanical switch but thats not an option for me. I want to do smething cool but dont have any experience with IC's. Thats why I asked. I can read prints and can build it fine. But I have never taken a course on it so I wouldn't know where to begin. I'm sure I could achieve my goal with 2 or 3 latching relays and a bunch of diodes but I just thought I'd ask you guys as some of you are very clever in this dept.

Mike

vrg3 · Post by **vrg3** » Fri Sep 05, 2003 9:15 pm

Ah, cool...

I was about to suggest you just do it with relays and diodes since you have more experience with them until I realized I couldn't think of a way to do this with relays. You really need your switching circuit to be edge-triggered, right? How do you do that?

If you use the 4017 setup, the schematic I posted is close to what you need. I'd put two 0.1uF bypass capacitors, from the input and output of the 7805 to ground. I think I got one of the pins wrong -- I put pin 12 as the master reset but I think it's actually 15.

You'll also probably need some kind of power-on reset because when the 4017 is first powered on its state is undefined. You could use a simple RC circuit: the output of the 7805 -> a capacitor -> a resistor -> ground. The voltage at the junction of the cap and the resistor would stay at 5 volts for a short time after power is applied and then would drop to 0 volts. You could connect that straight to pin 15 and use a diode to connect the other reset (from output 3 of the counter).

That ought to do it...

magicmike · Post by **magicmike** » Fri Sep 05, 2003 11:05 pm

Thanks alot, I should be able to get it. In the mean time I will also figure out how to do it with relays and post that for you. Just to pass some info on. Thanks again,

Mike

vrg3 · Post by **vrg3** » Sat Sep 06, 2003 2:15 am

Thanks, I'd appreciate having that bit of knowledge available.

Good luck building the circuit; let us know how it comes out.

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Any IC geeks out there?

Any IC geeks out there?