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  • Author Author: jw0752
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Before Solid State Logic there were Relays

jw0752

Here are a couple of interesting relays that I salvaged out of some older Dental X-Ray equipment. I am guessing they are 1960's era. The first one is a 24 VAC solenoid that uses a cantilever to switch between the activation of one SPDT micro switch or another.

 

 

The second relay that I want to show you is actually two relays set up in such a way that each one latches the other and each one resets the other. These are 120 VAC coils and they each have 3 PDT switch configurations so I guess it is a 6 pole double touch flip flop with set and reset inputs. As a bonus in these videos you get to hear my bad voice which is a result of an idiopathic paralysis of one vocal chord. The most serious result of this affliction is that I can no longer win arguments.



John

  • Hi John,

     

    What a great action and thank you for taking the time to record such interesting mechanics (otherwise these kind of things get destroyed and forgotten about).

     

    The action reminded me of a chicken pecking at grain image

  • in reply to DAB

    Hi DAB,

    When I was in High School 1965 the Math Dept coughed up the funds to buy me enough relays to build a 4 digit binary adder. I built it using mains voltage and neon lights for input and output indicators. Pretty scary by today's standards.

    John

  • Great post John.

     

    During my tech school days I worked for GTE and had to hand burnish relay contacts for certain equipment.

     

    We had one engineer who was experimenting with logic circuits using relays.  It was an interesting approach, but it took a lot of power and made a lot of noise.

     

    DAB

  • in reply to shabaz

    Thanks Shabaz,

    I have always enjoyed working with the electronic / mechanical area of interface. Relays still make up a good portion of my builds even though there may be better ways to accomplish the goals using solid state devices. To me there is something comforting about the isolation afforded by a relay and the hard contact of its switches. The voice doesn't hurt but I have very limited stamina and have to breathe more frequently during speaking as it takes more breath to make a vocalization. This can lead to light headedness if I have to speak for more than a minute or two. Over all a very minor affliction.

    John

  • Hi John,

     

    Great videos, very cool to see the mechanical operation of these devices! I'd not seen before how these things work.

    It might be vintage tech, but it still has its uses. I used a modern step relay (which does a similar function as the device in your first video)

    for implementing a push-on push-off system for a kitchen appliance - means I can have a simpler, cleaner push-switch than a latching or

    toggle type of switch.

    Similarly the second video shows a technology that is still great for control of devices while using low energy to do so, or where you might

    want to control something and maintain state in power loss. They are still useful relay technologies for such scenarios.

    Really interesting videos, and great to hear you - hope it doesn't hurt.