Yep. That's about what I was looking for. Thanks!

Although in the true radio switch it can be random selectable.
Max.

 

Although in the true radio switch it can be random selectable.
Max.

Yeah, I thought about that, too. But that would involve either (a) a complicated system of relays or (b) a microcontroller. Neither of which appeal to me (at this moment, anyway).

 

Could be an opportunity to get into it!
http://www.winpicprog.co.uk/pic_tutorial2.htm
http://www.winpicprog.co.uk/pic_tutorial.htm
Max.

 

Here's another related question...

I'm considering doing this project in the next few weeks. Instead of my test circuits, though, I'm going to use some toys circuits I built for my kid. All are 555-based oscillators. Can I attach four separate 555 output leads to one speaker, provided I use a small diode on each lead? Or must I use four speakers?

ETA:

I ask this question because only one circuit will be active at a time.

 

If only one circuit is active at a time it should be possible, the output of the 555 is push-pull.
If it were open collector outputs it is usually not necessary for the blocking diode.
Max.

 

Yeah, I thought about that, too. But that would involve either (a) a complicated system of relays or (b) a microcontroller. Neither of which appeal to me (at this moment, anyway).

A quad RS flip flop should make a one chip solution.

It wouldn't get too complex with only four switches and diode logic.

Pull up/down resistor on each R and S. As per type.

One momentary switch to each S. (to set Q)

3 diodes from each switch to the"not wanted" R (resets). (to reset others)

Outputs from Q1 thru Q4.

 

A quad RS flip flop should make a one chip solution.

It wouldn't get too complex with only four switches and diode logic.

Pull up/down resistor on each R and S. As per type.

One momentary switch to each S. (to set Q)

3 diodes from each switch to the"not wanted" R (resets). (to reset others)

Outputs from Q1 thru Q4.

Any particular IC I should look at?

 

I have to do a service call.
I'll check later.

Oh, I forgot an "all off".

4 more diodes?

 

CD4043 or CD4044 depending on high or low outputs needed.

http://www.intersil.com/content/dam/Intersil/documents/cd40/cd4043bms-44bms.pdf

 

CD4043 or CD4044 depending on high or low outputs needed.

http://www.intersil.com/content/dam/Intersil/documents/cd40/cd4043bms-44bms.pdf

Cool. Thanks!

Anybody else have ideas on how to do this?

 

Did you follow my description.

If someone agrees that it might work, I could draw it up.

 

Did you follow my description.

If someone agrees that it might work, I could draw it up.

I followed most of it. I'm still a bit of a rookie, but I got the general idea. Draw it up and lets take a look. Thanks for helping me out!

 

I followed most of it. I'm still a bit of a rookie, but I got the general idea. Draw it up and lets take a look. Thanks for helping me out!

Here's my first try.
Ignore "NOT Q" It's not available in the 4043.
Selected outputs go high.
Use 4044 if you want low.

http://www.intersil.com/content/dam/Intersil/documents/cd40/cd4043bms-44bms.pdf

 

And if you stick a 2N7000 on each output you can drive up to 60v at 200ma.
Max.

 

The diodes and drivers can be dip arrays also.

Like a 50V 500 mA darlington driver array.
http://www.toshiba.com/taec/components2/Datasheet_Sync/200910/DST_TD62083APG-TDE_EN_11446.pdf

Although, using only 4, the board layout would be easier using discrete.

I'm not an fet guy.

But I'm sure Max could show you the interface.

I haven't done a cmos project in years, but the regulation, bypassing, and pull up/down rules should pretty forgiving in a static switch app.

 

Here's my first try.
Ignore "NOT Q" It's not available in the 4043.
Selected outputs go high.
Use 4044 if you want low.

http://www.intersil.com/content/dam/Intersil/documents/cd40/cd4043bms-44bms.pdf

Ahh, now I see what you were talking about regarding diodes. That makes perfect sense. Are the resistor values critical? Or can I use the same arbitrary value on all pins?

 

The diodes and drivers can be dip arrays also.

Like a 50V 500 mA darlington driver array.
http://www.toshiba.com/taec/components2/Datasheet_Sync/200910/DST_TD62083APG-TDE_EN_11446.pdf

Although, using only 4, the board layout would be easier using discrete.

I'm not an fet guy.

But I'm sure Max could show you the interface.

I haven't done a cmos project in years, but the regulation, bypassing, and pull up/down rules should pretty forgiving in a static switch app.

Another good idea. Is the "common" pin connected to anything? Ground? Or left floating?

 

The driver was just an example.
One should be chosen based on your requirements of voltage and current.
Data sheet shows the 62084 a better choice for cmos over 5volts.
The 62083 is just one that I had a bunch of.
Along with:
62783
62003
62064
62004

The common is connected to the +supply, that supply the relays. It has the clamp diodes built in that would normally need to be connected across relay coil.

The pull down resistors value isn't important. IMO

Most switches like a fairly high value of current. I would go with something around 47K. I can't think of a reason why anything from 1K to 500K wouldn't work.

Diodes can be small signal type.

By the way I haven't built this. Nor have I looked for availability of parts.

I certainly wouldn't commit to this before bread-boarding or getting other opinions.

It's easy for me to get high/low logic mixed up.

It looks to me like a high to set=high to Q=low to the open collector drivers=relay pull in.

Another thing of course is power reset condition.
I'm assuming that on "power up" all Qs will be in the reset=low condition=relays off.
I haven't actually looked.

 

The driver was just an example.
One should be chosen based on your requirements of voltage and current.
Data sheet shows the 62084 a better choice for cmos over 5volts.
The 62083 is just one that I had a bunch of.
Along with:
62783
62003
62064
62004

The common is connected to the +supply, that supply the relays. It has the clamp diodes built in that would normally need to be connected across relay coil.

The pull down resistors value isn't important. IMO

Most switches like a fairly high value of current. I would go with something around 47K. I can't think of a reason why anything from 1K to 500K wouldn't work.

Diodes can be small signal type.

By the way I haven't built this. Nor have I looked for availability of parts.

I certainly wouldn't commit to this before bread-boarding or getting other opinions.

It's easy for me to get high/low logic mixed up.

It looks to me like a high to set=high to Q=low to the open collector drivers=relay pull in.

Another thing of course is power reset condition.
I'm assuming that on "power up" all Qs will be in the reset=low condition=relays off.
I haven't actually looked.

Thanks again, inwo. I'm going to think about these options over the next couple of weeks and then put 'em all to the breadboard. I'll make sure to check back in and give a report.

 

Never assume anything.

After research:

If you build this and power-up state is random we will have to add a "power up reset" circuit.