Progressive Relay Cascade Circuit, Latching - Suggestions Please

Thread Starter

BigBlueCar

Joined Sep 23, 2013
14
I'm hoping someone can help me with a circuit design problem. I've trawled this site and most of the web but can't find exactly what I need.

I have about a dozen lights (220V) that I want to switch on and keep on in sequence using relays.

There are loads of circuits to be found for LED cascades etc. but they all turn off the previous light when they light the next, so no good for me. Actuation is easy, I've got a couple of 8 way 240V relay boards with 12V control (originally for Arduino I think) and to trigger the relays all I need to do is take the relevant pin on the board to ground.

But I need to be able to ground those control pins in sequence and keep them that way, until ideally we can add a final trigger pulse to turn the lot off.

A variable time between each illumination would be a bonus, but if not, I'm looking at about half a second between each light.

I've looked at cascading 555 timers and decade counters but just couldn't figure it out properly. I could try with Arduino but my programming skills are very, very rusty so I'd really need it already done so that I can cut and paste. A series of timer relays would be easy to do, but would be so 1960s and I'd rather do it with the soldering iron.

If anyone has a circuit to hand that I can build from, maybe expand to more relays I'd be eternally grateful.

The overall scheme would be:
All 12V powered, no need for 5V
Relays on my board(s) need grounding at the pin to activate
Short trigger pulse (from a remote) to start the sequence
Relay 1 pin on the control board sees 0V to activate
0.5 seconds later (approx, maybe adjustable) relay 2 pin sees 0V, relay 1 pin stays at 0V
0.5 seconds later relay 3 sees 0V, 1 and 2 remain at 0V
Sequence continues until Relay X and all remain at 0V on the pin on the board and all energised
....
.... Some time later .........
...
Short trigger pulse (ideally on different contacts) and all control pins are un-grounded, relays switch off.
Many Thanks.
 

ericgibbs

Joined Jan 29, 2010
13,829
hi BBC.
Using a couple of 8 Bit Shift registers in series, clocked by a 555 would give a fixed On interval and an all Off option.
E

EDIT:

Checkout this datasheet.
 

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Thread Starter

BigBlueCar

Joined Sep 23, 2013
14
Brilliant, thanks for that. Looks like it's CMOS 5V though so no use to me?

If there's a 12V equivalent, can you point me at any example circuits I can expand upon?
 

ericgibbs

Joined Jan 29, 2010
13,829
Have you read the d/s regarding the output sinking capability of the TPIC, 250mA at 45Vdc, that should sink a typical 12Vdc relay directly.

The 5V is a trivial point, a cheap 7805 regulator driven from the 12Vdc supply would give a 5V logic supply for a 555 astable driver.
 

Thread Starter

BigBlueCar

Joined Sep 23, 2013
14
Thanks Eric, but what I'm really after is some ideas for circuit design, not the semiconductor(s) to use.

Someone, somewhere must have needed something similar to this before and I'm trying to avoid half a day with a breadboard seeing if I understand a data sheet properly.
 

eetech00

Joined Jun 8, 2013
2,595
Hi

There might be an easier way to this, but here's one way.

The Q1-Q8 outputs are normally high and would connect to your control board inputs. Each output goes latches low in sequence.
They are not intended to drive relays directly. However, they could be made to do so by modifying the outputs to drive mosfets that would drive the relays.

The start button initiates the sequence. The clock is inhibited when the last output (Q8) goes high. The reset button clears the latches resetting all outputs to the high state. The clock remains inhibited until the start button is pressed.

See attached.

RelayInterfaceSequencer-Ckt.png RelayInterfaceSequencer-Sim.png
 

Thread Starter

BigBlueCar

Joined Sep 23, 2013
14
I'm so grateful for that, it's perfect for my needs and the components cost peanuts.

Just two questions, if you'll oblige me:
  1. What do I use for U1? Is it another 4013B?
  2. If I need to extend to more than 8 outputs to get my dozen lights, presumably I just cascade another circuit, replacing the START button for the second set with Q8 from the first and putting both RESET buttons in parallel?
 

eetech00

Joined Jun 8, 2013
2,595
I'm so grateful for that, it's perfect for my needs and the components cost peanuts.

Just two questions, if you'll oblige me:
  1. What do I use for U1? Is it another 4013B?
  2. If I need to extend to more than 8 outputs to get my dozen lights, presumably I just cascade another circuit, replacing the START button for the second set with Q8 from the first and putting both RESET buttons in parallel?
Hi

1.U1 is a CD4093B Quad NAND chip

2. So you want this to be expandable? So that with two circuits you can cascade 16 outputs? Would an increment of 4 work better? I believe you would still only require a single start and reset input, so those wouldn’t need to be duplicated. I’ll wait for your reply..
 

eetech00

Joined Jun 8, 2013
2,595
Hi

Here is a 12 output version.
I decided on a 12 output version because it best the circuit runs on a common clock, and, the extra pushbutton circuitry would be somewhat wasteful. I also added a pot so the clock would be adjustable. I didn't show every output on the graph but I think you get the idea.
Each chip should have a bypass capacitor. Those are shown at the bottom of the schematic.

eT

RelayInterfaceSequencer4-Ckt.png RelayInterfaceSequencer4-Sim.png
 

Thread Starter

BigBlueCar

Joined Sep 23, 2013
14
Thanks once again EE, that's just perfect for my need and the parts are already on order. I'll warm up the breadboard and sort out a PCB design for the final project.

I assume the 250k pot replaces R7 and takes it's adjustable input from U1C?

Expandable to 16 ways would be an added bonus for later projects, is it just add U9 and U10 and keep on going?

I'm very grateful for you taking the time to draw something up. I'll report back on the result.

Ian :)
 

eetech00

Joined Jun 8, 2013
2,595
I assume the 250k pot replaces R7 and takes it's adjustable input from U1C?
Yes. R7 is a pot and, along with R5, C11, limits the frequency range to aprrox. 1.2 Hz to 3.7 Hz
R5+R7 and C11 produces a exponential waveform at the input to U1C that produces oscillation. U1D inverts the oscillator output so the clock starts at logic low. U2A-Q gates the clock.

Expandable to 16 ways would be an added bonus for later projects, is it just add U9 and U10 and keep on going?
That's basically the idea, but there are other considerations for making the circuit expandable.

I'm very grateful for you taking the time to draw something up. I'll report back on the result.
Ian :)
No worries...

However, I would like to review the Relay control board this will interface with. Each output is limited to max 6 mA. Do you have a part number or doc to share?

eT
 
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Thread Starter

BigBlueCar

Joined Sep 23, 2013
14
The documentation for the relay broad is non-existent, but for a fiver a time I suppose you get what you pay for.

However, this is effectively the same thing and gave me more than enough info to implement it - http://wiki.sunfounder.cc/index.php?title=8_Channel_5V_Relay_Module

Just give it 12V on VCC and ground any of the 8 pins to activate it's relay.

I should say that each of the lights is 8W, 220V LED, so the relays are more than man enough for the job.

Ian
Ian
 

eetech00

Joined Jun 8, 2013
2,595
The documentation for the relay broad is non-existent, but for a fiver a time I suppose you get what you pay for.

However, this is effectively the same thing and gave me more than enough info to implement it - http://wiki.sunfounder.cc/index.php?title=8_Channel_5V_Relay_Module

Just give it 12V on VCC and ground any of the 8 pins to activate it's relay.

I should say that each of the lights is 8W, 220V LED, so the relays are more than man enough for the job.

Ian
Ian
OK..just remember each output is limited to 6mA so you'll need to be able to limit the current of each to about 1-2mA.

eT
 
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