Electronics Fan-bus using momentary switches.. please read for explination

If you use my circuit, it only does 00 -> 01 -> 10 -> 00 -> 01 -> etc.

 

I dont think I need to worry about bounce if I get a decent switch do I?

What if I put a small capacitor in line straight after the switch, so you need to hold the button down for a second or soemthing..??

 

Yep, a capacitor in line might work, but double check with someone first. Not many switches will create no bounce. That's why they make special "de-bounced" switches with the gubbins inside.

 

Well Im gonna try and get all the stuff from my local Maplins so Ill take a look at which switches they have that look the part.

Could I ask another favour..
Will someone draw a quick diagram of one curcuit using an optoisolator to run a fan at 0/5/12V or 0/7/12V (doesnt matter which) please..? I think I get it but I want to make sure.

Thanks for all the help.. Mark

 

Instead of logic circuits about using a 4017B?


EDIT: I was bored so i knocked up a circuit diagram (i think it should work):


if this image doesn't appear try refreshing a few times, i'm having problems with my web-space


I'll get you the PCB artwork if you like, its a tricky one; if you are doing your own don't forget the HIDDEN DIGITAL POWER SUPPLY!

 

Oh my god, why did I never think of using that! I've even used one before, so I should have remembered really, heh. MarkDixon, use this circuit with the 4017B, it's much simpler and works just as well.

 

Most of my mods have a 4017B in them <hugs IC>

 

Wow. Thats brilliant.
Thanks a lot acrimonious, Thats gonna save me a lot of time and space making these things. A bit of an explination of the various parts would be great.. and the PCB artwork would be handy.

 

It's basically the same as the circuits already given, but the 4017B chip is performing the counting and decoding functions, so it cuts out all the messy logic stuff.

 

And whats the 'hidden digital power supply'?? Is this something to be concerned about..?

 

acrimonious could you also post a complete parts list for me, that would be excelent..

 

::EDIT::

 

MarkDixon, by hidden digital power supply, he just means the power to the 4017B chip, since it isn't shown on the diagram. It's just a connection from Vcc on the chip to the 5V line, and the ground connection. There will most likely be a datasheet on the site wherever you buy the chip from that labels these pins.

If not then it's easy enough to do a Google search for "4017B pinout" to get one.

 

Explanation of circuit:

When SW1 is pressed the 4017B recives a signal (it should not be sensitive enough to require a debounce circuit), it then latches open the next chanel in the sequence of 10 (0-9) (if 8 was latched open the button would switch the ouput to 9, etc), if the output is latched to 9 then the next press will reset the latch to output 0.

This latch then triggers one of three opto-isolators (Q1-Q3) which lets a current pass to the base of the apropriate transistor.

The transistor then lets current pass from the collector (top) to the emitter (bottom).

This triggers one of three things depending on which output is latched.

0, 3, 6, 9 - A green LED (D3) (with resistor R3) + Relay RL2 which lets 12v pass through to the FAN connector. Diode D5 protects componants from 'back EMF' caused by the relay.

1, 4, 7 - An amber LED (D2) (with resistor R2) + Relay RL1 which lets 5v pass through to the FAN connector. Diode D4 protects componants from 'back EMF' caused by the relay.

2, 5, 8 - A red LED (D1) (with resistor R1).

 

I managed to save the parts list so I can sort out the components.
I didnt understand one bit of the curcuit, I thought that it would need to have two presses of the switch to get off 12V but no I understand about when it resets.

Just a simple question, what is a rail??

 

A rail is a line, a wire, a connection. The 12V wire on your molex plugs could be (and often is) referred to as the 12V rail. So just replace rail with connection and you're generally ok

 

I thought it was something like that, Id decided it was like a power-splitter.. One end you have the + and then you connect everything off that... Almost right..

 

::EDIT::

 

USE THIS CIRCUIT INSTEAD:



Explanation of circuit:

When SW1 is pressed the 4017B recives a signal (it should not be sensitive enough to require a debounce circuit), it then latches open the next chanel in the sequence of 10 (0-9) (if 8 was latched open the button would switch the ouput to 9, etc), if the output is latched to 9 then the next press will reset the latch to output 0.

This latch then triggers one of three opto-isolators (Q1-Q3) which lets a current pass to the base of the apropriate transistor.

The transistor then lets current pass from the collector (top) to the emitter (bottom).

This triggers one of three things depending on which output is latched.

0, 3, 6 - A green LED (D3) (with resistor R3) + Relay RL2 which lets 12v pass through to the FAN connector. Diode D5 protects componants from 'back EMF' caused by the relay.

1, 4, 7 - An amber LED (D2) (with resistor R2) + Relay RL1 which lets 5v pass through to the FAN connector. Diode D4 protects componants from 'back EMF' caused by the relay.

2, 5, 8 - A red LED (D1) (with resistor R1).

9 - Reset to 0 (auto)

 

That parts list, should work now!: