36v DC and SSRs

M

mutleyrover

New member
I have got a variety of LED strings that all have wall warts which supply different voltages to the lights, some being AC and some being DC. This is what they supply:

24v AC

24v DC
25v DC
30v DC
31v DC
36v DC

I plan to use Renard controllers (plus 32, 64XC) with separate SSRs and group my lights together so that the 4 outputs from any one SSR will be the same voltage, that way I can use a single power supply in to the SSR to run all 4 sets of lights.

I therefore need some AC SSRs and some DC SSRs. As far as I can see the DC SSRs all seem to say that they can be used from about 6v to 30v DC. I'm therefore wondering if I can run my lights that require 36v DC. Is that too much power to put through the SSRs or will the boards stand up to 36v DC?
 
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There are two considerations here that I can think of. First, the transistors on the SSRs must be rated for higher than 36V if you are going to use a 36V power supply. I'd recommend using transistors (MOSFETs, most likely) that are rated for 60V or higher.

Some of the DC SSRs that are described here or in the wiki use DC regulators to drop the input DC voltage of the SSR down to a much lower voltage used for the optos and the gates/bases of the transistors. These regulators also need to be rated for much higher than 36V. Regulators that would withstand this higher voltage are much less common the regulators rated for 36V or lower, so it would take some research to find them.
 
Ok the occasion where I needed to run some dc SSRs at 36v, I cut the track between the input voltage terminal and the volt regulator and then inserted a string of 6xSMD diodes.
Another option is to insert a 7824 regulator, but that more complicated.

Sent from my SM-N9005 using Tapatalk
 
P. Short said:
There are two considerations here that I can think of. First, the transistors on the SSRs must be rated for higher than 36V if you are going to use a 36V power supply. I'd recommend using transistors (MOSFETs, most likely) that are rated for 60V or higher.

Some of the DC SSRs that are described here or in the wiki use DC regulators to drop the input DC voltage of the SSR down to a much lower voltage used for the optos and the gates/bases of the transistors. These regulators also need to be rated for much higher than 36V. Regulators that would withstand this higher voltage are much less common the regulators rated for 36V or lower, so it would take some research to find them.
Click to expand...

The SSRs that I was planning to use were the Renard Plus DC SSRs. On the Renard Plus website it says about them being suitable for between 6v and 30v. However, since I posted this I noticed that they've been added back on to Radiant Holidays website with the following description:

The Renard Plus DC SSRhc is a Solid State Relay with 4 independent DC output Channels. The input for the control power is a +5VDC via the RJ45 connector. Each channel is then controlled by sinking this control power for each of the Optoisolators for a given channel. The optoisolators then in turn fire the channel MOFET. The MOSFETS are good for up to 60V and a maximum of 4A each. The total board power is limited to 10A.

From that description, and that being a kit including the BOM, I assume that I would be good to go with running my 36v DC lights with 36v DC power going through the SSRs, supplied by a SMPS.
 
P. Short said:
Some of the DC SSRs that are described here or in the wiki use DC regulators to drop the input DC voltage of the SSR down to a much lower voltage used for the optos and the gates/bases of the transistors.
Click to expand...

I was just thinking about this comment. If I use an SMPS to supply the input voltage (in this case 36v DC), will the output voltage for the lights still be 36v? Is it the case that any regulators will drop the voltage for the optos, but not affect the voltage going through the board and out to the lights?

I'm not an electrician so my knowledge is limited, but I'm trying to learn!!
 
mutleyrover said:
I was just thinking about this comment. If I use an SMPS to supply the input voltage (in this case 36v DC), will the output voltage for the lights still be 36v? Is it the case that any regulators will drop the voltage for the optos, but not affect the voltage going through the board and out to the lights?

I'm not an electrician so my knowledge is limited, but I'm trying to learn!!
Click to expand...

Yes, for those DC SSRs that have an on-board regulator. It appears that you don't have to worry about this for the SSRs that you mention in post #5 above, based on what you wrote in post #5 (since I have no direct knowledge of those DC SSRs).
 
P. Short said:
Yes, for those DC SSRs that have an on-board regulator. It appears that you don't have to worry about this for the SSRs that you mention in post #5 above, based on what you wrote in post #5 (since I have no direct knowledge of those DC SSRs).
Click to expand...

Thanks Phil. Looks like they are probably the ones for me to go for. Just need to put an order in now!
 
Matt_Edwards said:
Ok the occasion where I needed to run some dc SSRs at 36v, I cut the track between the input voltage terminal and the volt regulator and then inserted a string of 6xSMD diodes.
Another option is to insert a 7824 regulator, but that more complicated.

Sent from my SM-N9005 using Tapatalk
Click to expand...

Thanks for this Matt. Does this resolve the problem? Have you maybe got any photos to show what you did?
 
Most of mine are packed away or in sealed boxes.
I only have the original dc SSRs.

I will see what I can do in a couple days.

Sent from my SM-N9005 using Tapatalk
 
David_AVD said:
You can use one lower voltage power supply to run the controller and a different (36V) one to power the actual lights.
Click to expand...

Having re-read it properly I understand it now. I guess the downside is having to have a multitude of power supplies!
I guess one obvious question is whether there are DC SSRs that exist that are able to take voltages higher than 30v?
 
That board could be easily assembled to use a shunt regulator instead of a series regulator because the pcb design has two series regulators in parallel. The parts would need to stand on end, but placing a resistor between the input and output of one regulator footprint and an appropriate zener diode between the ground and output of the other regulator footprint would do the job. The disadvantages are that the input voltage range is much smaller than the input range of a series regulator (such as the 78L05), and it draws power all the time, but it provides a way of dealing with input voltages higher than the 40V that most 78xXX regulators can handle.
 
P. Short said:
That board could be easily assembled to use a shunt regulator instead of a series regulator because the pcb design has two series regulators in parallel. The parts would need to stand on end, but placing a resistor between the input and output of one regulator footprint and an appropriate zener diode between the ground and output of the other regulator footprint would do the job. The disadvantages are that the input voltage range is much smaller than the input range of a series regulator (such as the 78L05), and it draws power all the time, but it provides a way of dealing with input voltages higher than the 40V that most 78xXX regulators can handle.
Click to expand...

I think I understand what you're saying here but I feel I'm rather at the far realms of my ability. I'm not an electrician nor do I have any background in electronics. While I feel happy to be able to follow instruction to build a board (from the wiki for example) I think I might be getting out of my depth with modifications. Maybe I just try and get lights that use 30v or less, and get rid of my sets using 36v. That feels very defeatist though!!
 
Matt_Edwards said:
Most of mine are packed away or in sealed boxes.
I only have the original dc SSRs.

I will see what I can do in a couple days.

Sent from my SM-N9005 using Tapatalk
Click to expand...


Thanks Matt.

I was wondering what the theory of what you do is? Why/how does it allow you to use 36v?
 
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