First try!.....................

You need a resistor in series with each switch to give a delay ( a pot in series with a resistor if you want to adjust the delay). As shown, the delay is determined only by the switch and supply resistances.

Also, if you add a 20V or so zener in series with the SSR input (anode to input) then you can get the desired delay with a smaller capacitor.

 

You need a resistor in series with each switch to give a delay ( a pot in series with a resistor if you want to adjust the delay). As shown, the delay is determined only by the switch and supply resistances.

Also, if you add a 20V or so zener in series with the SSR input (anode to input) then you can get the desired delay with a smaller capacitor.

If you put a resistor between the switch and the capacitor, you get a slow charge as long as you hold the switch down. They need an instant charge and slow discharge to hold the SSR on for a given time.

Ken

 

If you put a resistor between the switch and the capacitor, you get a slow charge as long as you hold the switch down. They need an instant charge and slow discharge to hold the SSR on for a given time.

Ken

Correct.

If OP wants to try this, I will do some more testing to see if 30sec. is even possible with reasonable ufs.

Resistance going into ssr may help increase T.

 

I did a little more digging. Circ motors are more like 1 amp though I imagine there is a spike at startup. The button needs to be a press and release and then the pump runs for 30 seconds... there is a lot of good leads and suggestions for me to explore. I appreciate all the comments.... For this to be a practical way of activating the circ pump from different rooms, the switch design needs to be simple, durable, rubust, and cost under about $30 bucks. thanks again for all the help and for any further suggestions!
John

 

I challenge anyone to come up with a less expensive simpler design. Than the ssr.

However the delay off relay I first linked will handle an amp by itself, and is probably the best way. $7.95 delivered.

Here is a 12vdc 0-3minute.................http://www.ebay.com/itm/12VDC-Power...530?pt=LH_DefaultDomain_0&hash=item3f0bdeb5b2

Also has other times and voltages for sale.

Only other thing you need is doorbell type switch and a 12vdc wall type supply.

If two times are needed use two relays. Else one relay will do both locations.

 

Just curious. Has anyone tried or simulated the circuit in post #18 for a 30/40 second on-time? I don't have a simulator or access to my lab today.

Ken

 

Will do it for real. Don't have much to do today.

 

Still had the test set up.
My little 14.5 charger wart has a little more voltage with some resistance in series.

All test were pretty much instant on/delay off.

2200uf @ 21.2vdc at cap. = 9.2sec.
2200uf @ 24vdc with 1k series to ssr = 14sec.
Same with 10K = 32 sec.
And with 15K = 29 sec. Diminished return!

10K and 4400 = 60 sec.

Does anyone question the diode steering?
Wouldn't take much to test.

 

Not to knock your circuit Inwo, but if there's an affordable off the shelf product that does exactly what I want, I almost always go that route. $7.95 is really hard to beat, and I saw some similar for even less. Factor in time to procure the components, build a circuit, and mount it in an enclosure (which you have to buy as well), and depending what $$ amount you value your own time at, the ebay timers are most likely the cheaper option as well as the easier one.

 

Not to knock your circuit Inwo, but if there's an affordable off the shelf product that does exactly what I want, I almost always go that route. $7.95 is really hard to beat, and I saw some similar for even less. Factor in time to procure the components, build a circuit, and mount it in an enclosure (which you have to buy as well), and depending what $$ amount you value your own time at, the ebay timers are most likely the cheaper option as well as the easier one.

I totally agree. See my other post.
We must think alike. I often post off-the-shelf solutions as best. For the reasons you listed. Often just the mechanics is a killer. Not to mention ul approvals etc.
Embarrassed to do it all the time as this is "all about circuits" forum.

Just playing with the ssr by request. And it's teaching me something!

ps. The little timer should run his little pump, right?
Thought 10 amps was high. My big grundfos circ. pumps are less than an amp. low inrush too.

 

If you put a resistor between the switch and the capacitor, you get a slow charge as long as you hold the switch down. They need an instant charge and slow discharge to hold the SSR on for a given time.

You're right of course. I was thinking backwards.

 

When I first looked at that circuit, that was exactly what I was going to recommend. Then I reread my post just before I hit send.

Ken