hey
im working on a project that will control 20 SSRs operating at 24 volts.
the relay board has a single input for the 24volt relay control circuit, and only require a short between the ground and the control pin for the selected relay. 24 volts will flow thought this short. i want to allow a microcontroller to run these relays i originally planned to use simple switching transistors to control each of the lines, but i wanted to use an IC as it would provide and neater circuit and less components.

Could i use the ULN2003 to contor the lines by just connecting the control pin for the the relay to the control pin on the uln chip.

Any help or ideas would be appriciated, i attached a image detailing the way i think it would be wired..
thanks
josh

Attached Images

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It should work ok, If the relays don't have a transcient protection diode across the coils I would connect the common pin of the ULN2003 to +24 so the internal diodes are the protection diodes.

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that is exactly what the uln2003 is for. just tie off the common pin to the 24V supply and you are off to the races.

 

well the problem i saw was that the ssr board uses a common ground and has its own power hook up,
so can the uln provide me with the short needed to trigger the solid state relays on this board

thanks
josh

 

Since your relays are solid state (no inductor), then you don't need to connect the common pin to +24. Your design will work fine.

 

Good to see the ULN2003 in another project

Just like mneary said, no need to connect the Common when non-inductive loads are being driven


BTW - why don't you use logic level SSR's?

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What are you controlling with the relays?

 

I bought the board and relays on ebay, i was looking to get some logic level relays but there 5 to 10 dollars a piece, i only paid 10 dollars for 20 relays and the board, i figure the buffer i need to make is well worth the savings.
I already have a pile of the uln chips i use them in alot of my projects they are a great little chip.

 

I will be using the relays to control a bunch of lights. i do small shows for christmas, halloween and any other time i find a theme.
This way i can move all the lighting control to a pic all its own. and connect them to the computer or another pic thats running the air valves, motors and everything else in the show.

 

ww.webbspinner.com

this is the board i was using to control just 8 channels of lights before, im hoping that the ssr board will be much neater, and more compact and faster along with tripeling my availible channels.
i will post come pictures of the new board when it is finshed, (that will be in a few months as all my electronics are packed and waiting to be moved to orlando.)

 

I made a Christmas light controller with a 555, 4017 and 4N25 optos in 1988. Only had to replace the interface board after a small fire in 1997. That project is boxed away after 3 years of no lights hung up. A schematic is available, and can be interfaced with ULN2003A for other applications.

 

im hoping my design will have significanly less parts, the controller, the buffers, and the relay board
Small parts count, easy wiring. and im using at 18F4550 so if i need to i can control it from my computer, at the moment im happy just writing the code for the microcontroller.
since i will have the extra ports im thinking of adding an lcd and RF remote to select different shows on the controller.

 

Hello gramo,

What program you are using to draw electrical circuit it seems interesting

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