Relay question

Jim Brain brain at
Fri Nov 28 23:13:41 CST 2014

On 11/28/2014 8:41 PM, Brent Hilpert wrote:
> I do have a design that sounds like what you want using 3 standard relays: one D/3PDT & two 4PDT (or, one D/3PDT, one 3PDT, one 4PDT), or probably best to just call it three 4PDT relays.
> A single NO pushbutton would control the relays, wired to produce a net divide-by-2 effect.
> Contacts on one of the relays would be used for the ON/OFF, in series with DT contacts on one of the others to direct the UP/DOWN.
> It's actually on-topic, as it's from a design exercise I did for the Simon relay computer.
> The (whole) schematic is linked on this page:
> See the top-left corner of page 2 of the schematic, the Ø, Øa & Øb relays.
> There's a timing diagram in the timing section on the web page, the Ø signal would correspond to the button pushes.
> It might be possible to reduce the number of contacts if one stared at the circuit long enough.
I looked at it for a while, and laid it out in Eagle, and I see what is 
going on.  Thanks for the idea.

I tried to simplify, but aside from using a few diodes to reduce the 
number of poles in the Phi relay, I see no way to get around needing 1 
4PDT (Relay A) and 1 3PDT (Relay B).  Still, it's a plan.

> Perhaps the solenoid-triggerred 'mechanical flip-flop' relay Brian pointed to is closer to what you want. One thing to note about that type is when the system is turned off it can be left in - and hence will power-up in - either of the two states, you wouldn't know initially whether it was going to go up or down, unless you knew from the last time it was operated.
Yes, I like your idea, because it always starts from a known state. But, 
at least I have two options.  I'll buy some 12VDC relays this week to 
wire it up.


Jim Brain
brain at

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