4 or more sequential, latching relay circuit

Thread Starter

Rick Weightman

Joined Sep 10, 2016
1
Hi, I'm looking for a device/ circuit that I can use to switch on a light display in sequence and will operate 4 or more relays in sequence with a delay between each latching relay, until a button or signal is pressed to turn the device/ circuit off.
I can construct a running circuit with one on, one off state but what I require I just can't figure. I thought about a PLC, but thought it could be built with semiconductors or maybe am Raspberry pi or similar?
Rgds, Rick
 

crutschow

Joined Mar 14, 2008
26,407
You could do it with a microprocessor, but it's fairly simple to do with discrete devices such as a 555 astable timer and a CD4017 decade counter plus some transistor relay drivers, which would operate up to 10 relays in sequence.
How much time between steps?
 

Bernard

Joined Aug 7, 2008
5,743
Let the on time of the 555 control relay on time & the off time control the delay. Use a two input AND gate for each non latching relay, a common input from all gates is from 555 output, 4017 outputs to other inputs, gate outputs to delay drivers.
 

crutschow

Joined Mar 14, 2008
26,407
Yes, I forgot that he wanted the relays to stay on after being energized.
For that, a simpler way would be to use a parallel-out shift-register such as the 8-bit 74HC164.
That wouldn't require any AND gating at the output.

LTspice of basic circuit below:
There needs to be transistor drivers added at the outputs to control the relays.
A momentary low of the RST signal resets the circuit outputs to zero and the sequence restarts when the RST signal goes high.
You could actually control up to 9 relays, if desired, with the first one controlled by the RST signal going high.

upload_2019-2-7_17-37-0.png
 
Last edited:

eetech00

Joined Jun 8, 2013
2,280
Hi, I'm looking for a device/ circuit that I can use to switch on a light display in sequence and will operate 4 or more relays in sequence with a delay between each latching relay, until a button or signal is pressed to turn the device/ circuit off.
I can construct a running circuit with one on, one off state but what I require I just can't figure. I thought about a PLC, but thought it could be built with semiconductors or maybe am Raspberry pi or similar?
Rgds, Rick
What supply voltage are you going to use and what type of lights?
 

eetech00

Joined Jun 8, 2013
2,280
Yes, I forgot that he wanted the relays to stay on after being energized.
For that a better way would be to use a parallel-out shift-register such as the 8-bit 74HC164.
That wouldn't require any AND gating at the output.

LTspice of basic circuit below:
There needs to be transistor drivers added at the outputs to control the relays.
A momentary low of the RST signal resets the circuit outputs to zero and the sequence restarts when the RST signal goes high.

View attachment 169718
That circuit won't work with latching relays...
 

djsfantasi

Joined Apr 11, 2010
7,400
Let’s make sure I understand your requirement. You need relays; I’ll use LEDs for example. You want the sequence LED1, then LED1 & LED2, then LED1 & LED2 & LED3 and finally LED1 & LED2 & LED3 & LED4. Then, a separate reset signal starts the sequence over again.

Am I close?

If so, I’ll look up one of Wendy’s old posts, which has a circuit to do this.
 

crutschow

Joined Mar 14, 2008
26,407
That circuit won't work with latching relays...
True.
I missed the TS mentioning that.
I see no reason to use latching relays, which tend to be more expensive, if you don't need them.
But if latching relays are used then my suggestion in post #2 should work,
 
Last edited:

AnalogKid

Joined Aug 1, 2013
8,943
That circuit won't work with latching relays...
I agree with Wally - the latching function is inside the shift register, so you don't need mechanically or magnetically latched relays. Also, with latching relays you need a way to reset all of them; either expensive dual-coil relays or a messy voltage-polarity-reversing-plus-a-bunch-of-steering-diodes gorp. The SR has a reset pin.

Rick - what is the load the relays are switching?

ak
 

eetech00

Joined Jun 8, 2013
2,280
I agree with Wally - the latching function is inside the shift register, so you don't need mechanically or magnetically latched relays. Also, with latching relays you need a way to reset all of them; either expensive dual-coil relays or a messy voltage-polarity-reversing-plus-a-bunch-of-steering-diodes gorp. The SR has a reset pin.

Rick - what is the load the relays are switching?

ak
Yes....but the TS might already have latching relays and changing them might not be an option.
This needs to be asked.

eT
 

AnalogKid

Joined Aug 1, 2013
8,943
That's where I was headed with the question about the loads. There might not be a reason to use relays at all, let alone latching ones.

ak
 

Bernard

Joined Aug 7, 2008
5,743
If the OP comes back we might get some answers. From long ago here are two bar graph suggestions.BAR Graph # 2 00000.jpg Bar Graph 00001.jpg Bar Graph 00001.jpg
As I said "repeating bar graph" How to git rid of # 2 ?
 
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