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daytimer
12-24-2013, 06:31 PM
Is there any reason you couldn't run 12vdc through a dirkcheap acssr instead of 120vac? As long as the current isn't too high....

dkulp
12-24-2013, 06:58 PM
I don't think they would shut off without a 0 cross from the AC line.

However, I have created semi-DC ssr's from the DirkCheaps. See:

http://www.diychristmas.org/vb1/showthread.php?296-DirkCheap-DC-SSR-kind-of&highlight=dcssr

Requires a slightly modified firmware for the controller though.

P. Short
12-24-2013, 07:17 PM
You can't use AC SSRs to control DC for the reason that dkulp stated.

daytimer
12-24-2013, 08:08 PM
Ok... I just stared at the schematics and researched further and now I think I understand why.
I thought the on/off/dimming zero cross was only controlled by (in my case) the Ren64. But, I think I see the difference in the chips that i didn't realize before....

MartinMueller2003
12-24-2013, 10:00 PM
I think you need to take a look at the info in this discussion. It will help you understand the importance of ZC. The Ren 64 does not control ZC. It detects it and reacts to it by refreshing the SSR.

http://doityourselfchristmas.com/forums/showthread.php?27514-Diodes-Rectifiers-SCR-Triacs-SSR-Huh&highlight=diodes+rectifiers

ppohlman
12-25-2013, 08:16 PM
Hey Dirk, is there a plan to make a DrikCheap DCSSR?

fathead45
12-26-2013, 03:00 PM
id like a board with just a single DCSSR channel on it. i have alot of dc elements that only need 1 channel and 2 grinchs to run them.

budude
12-26-2013, 11:03 PM
Hey Dirk, is there a plan to make a DrikCheap DCSSR?

I'm not clear what's being asked here? The DirkCheap SSR is cheap because it doesn't use a large TRIAC for the output but relies on the smaller TRIAC within the opto to do the work. I don't follow the context of this for DC? Are you just asking for a smaller DC output - something like the Ren48LSD does now? The biggest cost with the DCSSR is probably the MOSFET. Or are you just asking for a smaller form factor?

dkulp
12-26-2013, 11:40 PM
Probably a smaller form factor and hopefully cheaper DC SSR. My "hack" to the dirk cheaps uses a transistor, but that requires customer firmwares on the controllers and also doesn't provide any isolation. I was thinking of trying to experiment with sticking an opto-fet or opto-transitor. Either option would use roughly the same form factor of the DiskCheap. Obviously a much lower current that the full DC SSR (likely around .4A per channel looking at some of the specs), but for a lot of applications, that's probably enough.

ppohlman
12-27-2013, 12:01 AM
Smaller form factor, cheaper, no need to power large currents, and ideally able to run power along the network cable. I'd love to only need to run one cable to control and power 4 channels.

budude
12-27-2013, 01:47 AM
Probably a smaller form factor and hopefully cheaper DC SSR. My "hack" to the dirk cheaps uses a transistor, but that requires customer firmwares on the controllers and also doesn't provide any isolation. I was thinking of trying to experiment with sticking an opto-fet or opto-transitor. Either option would use roughly the same form factor of the DiskCheap. Obviously a much lower current that the full DC SSR (likely around .4A per channel looking at some of the specs), but for a lot of applications, that's probably enough.

I haven't seen where isolation has been that important for DC controllers - - there are 300+ Ren48LSD's out there representing over 14,000 channels and have never seen a case where the high load power somehow got back through the PIC, back through the RS485 chips and back to the PC - ever. It would be easy to just recreate the output portion of the Ren48LSD - it would still require the flipped outputs, etc as you do today if using a Renard non-SSR controller or even with an Arduino type output. Breadboard out with some cheap transistors and 470 ohm resistors - done...

dkulp
12-27-2013, 09:44 AM
I may be thinking a bit too logically (literally, I'm thinking logic gates), but I also had a thought of using a hex inverter (I haven't seen a quad inverter) to flip from sink to source to then drive 4 transistors. However, that would require board space for 4 transistors, 8 resistors, and a 14 pin chip. Might start getting a bit bigger. Not really sure if the inverter thing would work either. Something to breadboard up and experiment with.

MartinMueller2003
12-27-2013, 12:40 PM
I may be thinking a bit too logically (literally, I'm thinking logic gates), but I also had a thought of using a hex inverter (I haven't seen a quad inverter) to flip from sink to source to then drive 4 transistors. However, that would require board space for 4 transistors, 8 resistors, and a 14 pin chip. Might start getting a bit bigger. Not really sure if the inverter thing would work either. Something to breadboard up and experiment with.

FYI: The PIC code has the ability to output its signals using active high or active low modes. Leave out the inverter and change the PIC.

budude
12-27-2013, 01:16 PM
I may be thinking a bit too logically (literally, I'm thinking logic gates), but I also had a thought of using a hex inverter (I haven't seen a quad inverter) to flip from sink to source to then drive 4 transistors. However, that would require board space for 4 transistors, 8 resistors, and a 14 pin chip. Might start getting a bit bigger. Not really sure if the inverter thing would work either. Something to breadboard up and experiment with.

You only need four resistors to limit the current to the transistors from the PIC so the circuit could be quite small - smaller than the current dirkcheap AC board for sure.

dkulp
12-27-2013, 06:01 PM
Yea, if you look at my pictures and the description and such from my thread at:
http://www.diychristmas.org/vb1/showthread.php?296-DirkCheap-DC-SSR-kind-of&highlight=dcssr

that's what I did. However, I'd like to have a solution that doesn't require custom firmware changes. With the RenardPlus boards with the programming headers, it's not a huge deal, but it is a bit more involved with the other boards. Plus, you then need to remember (or record) which channels are source and which are sync and such.

MartinMueller2003
12-27-2013, 06:12 PM
I have a version of the renard PIC code that allows you to change the active high/low setting per channel at run time (download a configuration to the pic over the RS485 interface). Happy to give it to you.