pcb impulse relay? ...or 'stepper', 'ratchet', 'sequencing'

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fripster
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Post by fripster » Fri Jun 13, 2008 5:50 am

found it:

http://www.the12volt.com/relays/page5.asp

have fun!

fripster
Once a WireHead, Always a WireHead

geb
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Post by geb » Fri Jun 13, 2008 7:54 am

fripster,

First of all, sincerely thank you very much for assisting me in the search.

But I noticed that site early on too. On the one hand, using four relays to accomplish this as in one example is completely negating the point of keeping down the size dimensions and weight, especially when, after accomplishing this, one could simply have gone ahead and purchased the magnecraft 711 series, or the TYCO one that externet linked, and been done with it. I just don't understand the reason for the 12volt.com "special apps" relay page. It's a little absurd. It's an exercise in logic fun for mensa types perhaps, because most of it can be done more effectively with other already available relays. The page just assumes that all one has on a deserted island is a bucket of spst non latching relays, "so let's see what we can do with them".

Here is a vastly superior page...
http://tams-www.informatik.uni-hamburg. ... flop4.html
with a clever applet that shows what is going on. And, again, I have to wonder how it's possible that someone put all this effort into the problem and relay suppliers tell me there is just no need for this. I guess it's just a fine balancing point between the number of people who need this thing and the cost effectiveness of marketing one.

I actually have been banned from the12volt.com because I asked about the 13th example on that page, which looked promising. How do you return the arm on the latching relay that is shown in the diagram? There is no provision in the diagram for reversing polarity? Noone answered me for days. I bumped the thread and the forum mod told me that the latching relay in the diagram is a "special type, with a 'ball point pen type' mechanism for ratcheting the relay with each pulse. It does not need reversed polarity".

I responded with a plea to tell me where to find such a relay. A day later he said that he believes he personally bought the last remaining stock of such relays from a manufactuer several years ago. I then asked why the diagram was still posted at his site and he just ignored me. In my immense frustration, I guess I got a litte unhinged with my next post and got permanently banned. Still no explanation, and the diagram is still there. I am banned. The diagram does not work. You cannot buy the parts to make it work. Astonishing. What is the page there for?


externet,
wow... I'm flattered and thankful that you looked so far into this. I hope it is because you share just a little of my compulsion to solve this thing.
The 12vdc dpdt one from TYCO that you linked is the most promising. It's exactly the form I need but at three by two inch block of space is just not available in this project. It's similar in size to the Magnecraft 711, which I can find less expensively, but magnacraft has another catch.. magnecraft uses an IC timer based microcontroller inside instead of a cam to enable impuse mode. Back where I started. I can get a microcontroller flip flop at MCS pretty cheaply. It won't maintain status with power removed so I'd have to add a battery. I'd have to deal with the HF. I don't know if the magnecraft will maintain its setting with power removed either.

So home automation is become a big deal. I looked up X-10 standards and the very first hit was a wikipedia entry. On the page, to my utter astonishment, was a photograph of the relay I'm looking for!
http://en.wikipedia.org/wiki/X10_%28ind ... tandard%29
(click on the second photo down for a close up)
But I can't buy one, and manufacturers tell me there is no application for one. Household automation.... no market.... come again??

This has been such a bizarre odyssey that I'll be glad to be beyond it. I've never felt so dogged about something so small, and it worries me a bit. Maybe I'm becoming obsessive compulsive. But every tinkerer/designer must have a little of that to succeed.. no? To be told that something so simple, and apparently not entirely obscure (google is littered with attempts to accomplish this very thing with microcontrols and spagetti logic applied to ganged relays) is unavailable has just blown my mind.

Engineer1138
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Post by Engineer1138 » Fri Jun 13, 2008 8:33 am

This is the second time this week I've accidentally deleted a post {sigh} so I'll try to remember what I said.

Basically, sometimes you just can't find what you need off the shelf and it has to be built from scratch.

My approach would be one of these two:
a) get a small solenoid and make a rotary cam to close the contacts as needed from sequential activations. Heck, if I were going this far, I'd just make a momentary contact DPDT pushbutton and forget about the solenoid.

b) build the relay controller from 12V CMOS electronics for noise rejection and house the entire thing in a small aluminum enclosure grounded to the chassis.

Both of these need mechanical bits made, but that's why I have a lot of tools.

I understand that philosophically it may seem uncomfortable, but unusual requirements can conspire to make a seemingly simple problem quite difficult to solve.

-Lyndon

geb
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Post by geb » Fri Jun 13, 2008 8:39 am

Oh, and externet I never really did answer.

The coil voltage/current is going to have to be in line with the tolerance of available tactile switches. 12v or less and low current (unless I'm going to go adding another relay yet between the tact switch and the latching relay.. whew!)

The dpdt contacts that I need will switch 120vac at less than 500ma each.
You see why the big power relays are such overkill. But raw amp capacity doesn't really seem to be a limiting figure for pcb components these days.
There are automotive microminiature board relays out there that are capable of 30amps load and up.

fripster
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Post by fripster » Fri Jun 13, 2008 9:06 am

hi,

i once worked with an automotive pulse relay from siemens that did just this. pulse-on pulse-off. if I could only remember the type.... it was an automotive high-amps relay spdt for 12VDC in a metal casing. The mechanical outline was like a normal auto relay, the kind you use for headlight switching.

if i find it, i'll post it here

fripster
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Externet
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Post by Externet » Fri Jun 13, 2008 3:05 pm

Hi geb.

http://radiomagonline.com/notebook/radi ... _switch_2/

Just use a 3+PDT relay and tailor values to its specs. Very, very simple clever passive circuit, award winner. :shock:

Let me know if you are still not pleased.

Miguel
- Abolish the deciBel ! -

Engineer1138
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Post by Engineer1138 » Fri Jun 13, 2008 4:56 pm

Doesn't he need it to remember its state with the power off?
Externet wrote:Hi geb.

http://radiomagonline.com/notebook/radi ... _switch_2/

Just use a 3+PDT relay and tailor values to its specs. Very, very simple clever passive circuit, award winner. :shock:

Let me know if you are still not pleased.

Miguel

geb
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Post by geb » Fri Jun 13, 2008 5:46 pm

I do need that feature. Looking at that diagram it does look like it will default when power is taken away. For my project, if the operator chooses A, when the machine is turned on again, A must still be that state.

I'm more and more convinced that this is going to be a mechanical solution. So far in my journey I've found dozens of guys trying to accomplish this for special effects lighting, automotive mods, home automation, hifi audio projects, amatuer robotics, RC controls, and etc. On an RC forum I actually found a thread full of posts describing servos attached to latching switches as a workaround to the absence of this type of relay on the market.

Maybe the problem is that this (diy, hobbyist) niche is disappearing. It's crazy. Despite the presence of forums such as this, and places like hack-a-day, etc, there are really fewer and fewer (by raw numbers) individuals out there who seem interested in this stuff.

I live in West Michigan, and have to go fifty miles to Grand Rapids to get anything like what used to be commonly available in local hobby shops and Radio Shacks. Now the hobby shops are shuttered up, replaced by video stores and nail salons, and the radio shacks are basically storefronts for the cell phone companies. Even when I go to Grand Rapids I'm often demoralized by the difficulty in finding diy items from suppliers. They aren't used to dealing in small retail sales, and more often than not, they tell me that I can "find that online".

That is, of course, nonsense. Noone goes online to get a single solenoid, or a dpdt momentary switch, or a relay, or thermistor, unless your boss is paying the shipping for something that is needed overnight. It's just become impossible to do fun tinkering anymore it seems. Everyone says there's 'just no market for it'.

Another unsettling part of this, (from a U.S. point of view, with apologies to international members here) is that I often find links to pretty much exactly what I need... and these items are offered by companies in Germany, Japan, Poland, Singapore, and a few others. I can only imagine that the reason much of that is not to be had at U.S. distributors like Newark, Digikey, Mouser et al, is that there is, indeed, no 'market' for it here. Scary stuff indeed.

Oh well, enough rant.

Engineer1138
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Post by Engineer1138 » Sat Jun 14, 2008 11:51 am

geb:
Well, maybe that's your answer: build a few and sell them to the people who need them. That's how most successful businesses are started.

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