a 12 amp switching box
Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=124883
Printed Date: May 12, 2024 at 6:50 AM
Topic: a 12 amp switching box
Posted By: jef_a
Subject: a 12 amp switching box
Date Posted: December 07, 2010 at 6:13 PM
HI,
I need to design a control box for lights to be used in a theatre show.
The box will be foot operated, and control three lights (call them A, B , C)
--> Only one light is on at a time.
Ideally the box has FOUR buttons::
Punch button 'A' and light A comes on (light B & C off)
Punch 'B' and light B comes on (light A & C off)
Punch 'C' and light C is on (B & A are off)
Punch 'Off' and all lights are off.
Each light runs on 24v, 250 W, so drawing about 12 amps. I have had trouble finding triple throw switches that could do the job. Rotary are no use (impossible for foot operation), mini-toggles and guitar designed foot switches tend to be too small amperage rating.
At the moment I am using a simple system of three DPDT switches in a 'series' that are (barely) foot operable:
-switch 1: turns switch 2 on, or all lights off
-switch 2: turns switch 3 on, or turns light A on
-switch 3: turns light B on (C off) or light C on (B off).
Too much switching though.... argh! I need to be able to just jump from one light to another quickly, and without delay.
Is there a simple design using a RELAY that could get the job done?
I am just a hobbyist, with no formal electronics training but happy to hear DIY ideas and learn more.
Thanks- jeff
Replies:
Posted By: oldspark
Date Posted: December 07, 2010 at 7:35 PM
You want to use momentary push buttons?
IE - push B and B stays on until another button is pressed.
I think I have answered my own question, but just in case you (only) have latching switches - eg, toggles, DPDT etc.
Note that the guitar switch's current rating is simply increased by adding a relay for each switch.
An alternative to relays may be MOSFETS - especially depending on whether momentary or latching switches (and if xPST or xPDT).
And if MOSFETs, can the lights be controlled in their -ve leg (ground)?
FYI - Suitable MOSFETS for ground switching are only ~$3 each and have the advantage of silence (handy for rock gigs) plus potential for later electronic controls (for when you hit retirement age, or want a pay increase as a "lightshow programmer".
Posted By: hotwaterwizard
Date Posted: December 20, 2010 at 9:42 PM
 ------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: hotwaterwizard
Date Posted: December 20, 2010 at 9:58 PM
You forgot to tell if you are dealing with AC or DC Voltage.
You can buy 24v Cube relays AC or DC but if you want to use standard relays here is the pin number translation
------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: jef_a
Date Posted: December 21, 2010 at 5:15 AM
Hi. Thanks for the diagram.
But I see that I left out a simple detail in my original description.
Once each light is activated, I need to be able to take my foot OFF the switch, but still the light stays on.
E.g.: - Press 1 and light A comes on.
- A stays on with foot OFF of switch, until you ...
- press 2 and light B comes on and A clicks off. etc...
Only one light is on at a time, but once on they stay on until another light is activated, or none at all.
So, I am not sure that momentary switches are suitable . What type of switching system is this called?
Posted By: 91stt
Date Posted: December 21, 2010 at 10:09 AM
HWW's setup is latching so you will be able to remove your foot
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This information is provided only as a reference.
All circuits should be verified with a digital multi-meter prior to making any connections.
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