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I'm trying to make a circuit WITHOUT the use of any IC's or micro controllers. I'm basing it so far off of the circuit in the picture. Im planning on adding a flip flop circuit to it to make it the light stay on when you touch it.

The issue I'm having though is that this circuit would only light the led in one color. I have a 4 pin led and my end goal is to have the circuit able to switch between each color every time you touch the "button".

Ive been stumped on this for days. There has to be a way to wire this up manually so I don't have to use an IC or a micro controller right? enter image description here

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    \$\begingroup\$ You're going to have a hard time doing this without some sort of counter (or Johnson counter) IC. Of course you're stumped. \$\endgroup\$ – Bradman175 Jul 25 '17 at 0:16
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    \$\begingroup\$ Look up the SCS circuit (it's a latching circuit). Derive from there. If I can figure out myself I'll post an answer. And of course it's possible, it's just going to be complicated. \$\endgroup\$ – Bradman175 Jul 25 '17 at 0:22
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    \$\begingroup\$ Just use a micro. This is almost trivial for whatever little 8-bit 8-pin PIC, AVR, or anything else really. In the days you've spent getting nowhere you might have already been done. \$\endgroup\$ – brhans Jul 25 '17 at 1:24
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    \$\begingroup\$ What is it with so many beginners insisting on doing things without using ICs? Is it a hipster thing? Fear of having to solder SMT components? \$\endgroup\$ – Jeanne Pindar Jul 25 '17 at 3:42
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    \$\begingroup\$ @JeannePindar - I think it's the feeling that if something's easy, you're not doing it right. \$\endgroup\$ – Jules Jan 11 '18 at 7:57
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If you create the following circuit: enter image description here (Which came from here page 39)

...and then try to use your touch switch circuit so that it pauses the chaser, you can achieve what you want. Of course this means if you touch the button long enough, you can cycle multiple colours, but view it as a feature! ;)

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Stepping through the three LEDs in sequence requires a ring counter, a form of circular shift register. There are many ways to grow one from scratch, but none are as simple as a CD4017.

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  • \$\begingroup\$ This is the obvious best solution for simplicity. route stage after last used back to reset to reduce cycle length for rotating colors. then driver current depends on LED and buffer may be needed. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Sep 2 '17 at 20:24
  • \$\begingroup\$ 74HC4017 has about 150 ohms ESR @5V \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Sep 2 '17 at 20:31
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You say you don't want to add any ICs but then you say you are planning on adding a flip-flop, so I am not sure what you really mean by IC. But since you are willing to consider a flip flop I have a suggestion.

If I were you I would consider designing a logic circuit from 4000B series CMOS logic. They are cheap chips so you can buy lots of them for as many of these things as you are inclined to build. It also has all the useful functions that you will need: flip-flops, counters, and all the other useful operators. The other good thing about 4000B series is that it can take +15V (or more) power rails. Designing from CMOS logic will give you a more robust and reliable circuit than trying to use only transistors and passives, (I promise.)

You will probably want to use the 4000B series CMOS to drive bjt's that switch the led because the output current drive of the logic isn't great. This isn't a problem.

I think your control logic may get a little complicated at first pass, but it is a fun problem (at least I think so.) It will give you an opportunity to get clever and get a working circuit! Check out: CMOS Cookbook; Author ‑ DON LANCASTER for a good reference. Good luck.

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