I have a flow switch providing detection of DHW draw off.
I want it to operate a pump ... but not straight away (i.e. small am mount of DHW drawn off) anybody know a simple way to delay a main signal.
If it were LV could do it easy with an RC circuit, but this is all 220Vac
Can you get relays with a built in delay ? (220V coil)
I could create a LV supply and timer cct but wondered if there was a simpler way.
555 timer driving a solid-state relay, or 555 timer driving a bipolar transistor driving a conventional relay
Time Delay Relays are common - £20 upwards - look at RS components or I'm sure many others.
Cheers
NTC thermistor perhaps?
THere's a few ways that involve thermal mass instead of a capacitor to create a delay.
There are loads of different timer relays in the CPC and RS books (for instance). Many are multifunction. I don't think there's any permutation that can't be done. You want one called 'on delay'.
From the manual for a gadget I made last year:
"On delay relay (Relay 4). When the external supply comes on it is connected to Relay 5 after a delay. When the external supply goes off it is disconnected immediately."
Bill
Agree but then need LV to power the 555 as explained trying to do this all in 220V ac
I just found this item ....
anybody used these, may do what I need
So this thing
is likely to be what I need ... cheap enough
That looks alike a LV coil and AC contacts.
Is that what you wanted?
there are several. Provide more detail.
NT
Yes except it only has a series of fixed delays rather than infinitely variable.
Bill
No the illustrated one says it has a 220V coil. Personally I'd want one that was 235V if it's going to be activated for long periods.
Bill
I thought it was only going to be activated whilst the hot water was running? Does that qualify as "long periods"?
Tim
I suppose it depends on teenage daughters.
Or sons, these days.
Owain
# Ordered one of the ones I listed ... only a £5 They use an OMRON timer which are well used I ordered a 200-230vAC coil with 5A contacts
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