I want to control 6 LED's with 6 spst momentary switches. When no switches are pushed, no LED's are lit. When switch 1 is pushed, LED 1 lights and remains lit after switch 1 is released. If switch 2 is then pushed (and released), LED 1 turns off and LED 2 turns on and stays on. (etc for all switches)

Where should I start? Thanks in advance for your help!

 

What's the ultimate goal of this? You could probably do it with a series of Set/reset flip flops on each switch, but I don't know the best way to configure it.

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I'm going to use it to control relays for a test fixture. If I use set / reset flip flops, how do I wire it so pressing a "new" switch turns off the currently lit LED?

 

The simplest way would be to use a small microcontroller, it could all be done with just 1 IC. If your not into microcontrollers another way is to use set/reset flip flop IC's 4013 comes to mind. a pushbutton connected to the set pin turns on the latch which turns on the led. Then a short pulse is fed back to the reset inputs of all the latches to cancel any previously on led's.
That is the basic idea. I would post a schematic but I don't have a good schematic program.

 

Why don't you use the relays?

Button 1 operates relay 1, Button 2 operates relay 2, etc.

The relays have a holding path through the NC contacts of the higher numbered relays, ie. when R2 operates, it releases R1 & when R3 operates, it releases R2, etc.

You would need a reset button to release the last relay once it has operated, ie. when you want to release it.

If you don't know what I mean, let me know and I'll post a circuit for you.

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Len

 

Will they always be pushed in the same sequence, or is the sequence random?

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Ron (aka Rube)

 

hi digger,

If you have free choice of the type of switches you use, you can purchase a bank of 6 mechanical interlocking switches.

Any switch pressed holds in and releases any other.

Depending how much current you are switching, you may not require any relays. The switch elements come in N/O or N/C or change over.

EricG

 

Ok:

1 - To ljcox and ronh- The relays won't necessarily be used in a specific order so I can't trigger relay 2 off of relay 1.

2 - To ericgibbs - I can use a mechanical switch bank. But this isn't as much fun as doing it electronically. The only place I found that sells these types of switches (a custom switch manufacturer) has a 500 piece minimum order. Do you know of anyplace that sells eaches?

3 - To brever - I don't have any microcontroller experience but I could probably get something to work given some guidance. Which specific microcontroller would you start with? Regarding a flip flop circuit, if you can't post a schematic because you don't have the right software, can you just hand draw something and scan it to post?

Thanks all for your assistance!!!! This is a great site!!!!!!!!!!!!!!

 

hi digger

In the UK, RS Ltd sell individual switch kits.

I'll look at their website and let you know.

EDIT: www.rswww.com

stock no
333-726 DPCO latch sw £1.75 GBP
333-760 6PCO latch sw £2.79
333-625 Latching Bar £1.70

I understand the fun part, but its nice to have a safety net.

EricG

 

Do you mean that if say relay 5 is operated, then you may wish to operate R2?

In other words, is the choice random?

Or will it be only in a forward sequence, eg. R4, R6, R9, etc.?

Either way, then it can be done simply with relays.

What do the relays drive?

Are they to switch a high voltage?

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Len

 

3 - To brever - I don't have any microcontroller experience but I could probably get something to work given some guidance. Which specific microcontroller would you start with? Regarding a flip flop circuit, if you can't post a schematic because you don't have the right software, can you just hand draw something and scan it to post?

I would use a PIC microcontroller, I frequently use the 16F630 it would work very well in your application. It has 12 I/O lines, needs no crystal and costs about $1.80 US. I will see what I can do about a schematic, I dont own a scanner either. Where are you located ? I could just mail you something.

 

to ljcox - The final device is a test fixture for testing low pressure gauges. The gauges read from zero to 60 Cm H2O pressure. I want to push a button and the system pressurizes to 10 Cm H2O for example. I then read the gauge being tested to verify it is at 10. Then I push another button and the system pressurizes to 20. Another button for 30, etc. But I may also want to test to 10 then 60 then 30 then 60 again, etc so it is random and selectable by the person doing the test.

I will use the output to drive multiple 12v dc solenoid valves (maybe through relays or maybe just through transistors used as a gates), each solenoid valve is connected to a preset pressure regulator.

to Brevor - I live in Florida (USA)

to EricG - Thanks, that looks like it would work. I'll see if I can find something similar in the US.

 

to Brevor - I live in Florida (USA)

It sounds like we both have similar jobs, I also build test fixtures for use in the plant I work at. I have a lot of "off the shelf" designs I use and probably have something like you are looking for. If you would like by clicking on my user name you can e-mail me your address and e-mail I could most likley send you something like you need.

 

Understood, I'll post a circuit for you later today.

You did not say how many solenoids there are, But the circuit is easily expanded to how ever many you want.

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Len

 

This ain't elegant, but you can do the logic with four 74HC10's, two 74HC02's, and three 74HC74's. Or, if you need 12 volt logic, a similar solution is doable in CD4000 series. The microcontroller solution is much better if you can do the programming, or get someone to do it for you. Of course, if Brevor comes through, your problem is solved.

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Ron (aka Rube)