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View Full Version : Any Cheap DC SSR's?



Drweird13
09-11-2012, 08:31 AM
Hi,

I'm familiar with the DirkCheapSSR's and was wondering if there is anything equivalent in a DC form?

--Brian

jklingert
09-11-2012, 09:27 AM
You can always get some dc ssrs from here (http://www.diyledexpress.com/index.php?main_page=index&cPath=13) . Another option that some folks are using are the rgb amplifiers like these (http://www.diyledexpress.com/index.php?main_page=product_info&cPath=10&products_id=130) .

Mactayl
09-11-2012, 09:40 AM
Might be able to do that with some 6 pin dip mosfets and make a small pcb say 4 channels or even 8 channels

Mactayl
09-11-2012, 11:23 AM
Might be able to do that with some 6 pin dip mosfets and make a small pcb say 4 channels or even 8 channels

I Need to check on something like this on a small pcb.

http://components.omron.com/components/web/PDFLIB.nsf/0/C9B98832F2E6F97785257201007DD5AF/$file/G3VM_61B1_E1_1210.pdf

dirknerkle
09-11-2012, 11:36 AM
I Need to check on something like this on a small pcb.

http://components.omron.com/components/web/PDFLIB.nsf/0/C9B98832F2E6F97785257201007DD5AF/$file/G3VM_61B1_E1_1210.pdf

Mac, that looks like a nifty solution -- same pinout as an MOC3023 I believe... and about the same control current. I wonder if this could be almost a drop-in for an A/C SSR board without the triacs and substituting DC power for the normal A/C... Hmmmm.... solder a jumper wire in and you're almost good to go...

imbluenote
09-11-2012, 12:33 PM
I have some unbuilt ssrez's and could use a couple more dcssr's, might have to order some of these to try it out. (if someone doesn't do it 1st)

Mactayl
09-11-2012, 12:47 PM
I am going to order a few samples and see how or if they work.

kychristmas
09-11-2012, 01:07 PM
Doesn't seem like this is a solution for a DC version of the Dirk Cheap SSR. The cost per channel is going to be equal to or greater than the curent DC SSR used by many members. Am I missing something?

tstraub
09-11-2012, 01:17 PM
Why not make a Cheap DCSSR using the same 2222 transistors we already use in the Ren48LSD, SR RGB+W and other designs that are already proven solutions? the 2222's are only a few cents and have similar current ratings as this chip.

Mactayl
09-11-2012, 01:23 PM
Why not make a Cheap DCSSR using the same 2222 transistors we already use in the Ren48LSD, SR RGB+W and other designs that are already proven solutions? the 2222's are only a few cents and have similar current ratings as this chip.

That is another very good option

ErnieHorning
09-11-2012, 01:31 PM
The Omron part can also be used with low voltage AC.

Mactayl
09-11-2012, 01:34 PM
The Omron part can also be used with low voltage AC.I read that also in the specs...:thup2:

Mactayl
09-11-2012, 01:38 PM
Doesn't seem like this is a solution for a DC version of the Dirk Cheap SSR. The cost per channel is going to be equal to or greater than the curent DC SSR used by many members. Am I missing something?


I think with a very small pcb (4 channels or 8 channels) the cost would be quite low

ErnieHorning
09-11-2012, 01:39 PM
It shows using one FET or paralleling the two FET’s to double the DC current.

It doesn’t mention that you could also use the two FET’s separately at different voltages too.

dlovely
09-11-2012, 01:49 PM
Looks like it has a 500mA limit. So cost is going to be higher than the DCSSR solution now that can drive upwards of 2A. The 2222N can do the same a a huge cost savings.

Mactayl
09-11-2012, 01:52 PM
There are other devices that will handle 1.2 amps

Mactayl
09-11-2012, 02:06 PM
I am looking at the possibility of a small compact PCB that has sockets for the output driver and maybe the possibility's of changing it over to AC instead of DC as Ernie was saying about they can work with AC voltages also,,, this is all up in the air right now but it does seem like it can be a versatile solution,,, just thinking...

Drweird13
09-11-2012, 07:26 PM
For two pennies a piece...
http://www.ebay.com/itm/SALE-New-100-pcs-X-2N2222-2N2222A-PNP-40V-0-8A-Transistor-TO-92-Free-Shipping-/190710404526?pt=LH_DefaultDomain_0&hash=item2c6739d5ae

P. Short
09-12-2012, 10:20 AM
For two pennies a piece...
http://www.ebay.com/itm/SALE-New-100-pcs-X-2N2222-2N2222A-PNP-40V-0-8A-Transistor-TO-92-Free-Shipping-/190710404526?pt=LH_DefaultDomain_0&hash=item2c6739d5ae-

Be careful - the TO-92 packages usually have a lower current rating than a TO-18 package. Because they are in a TO-92 package, they are probably not a 2N2222 or 2N2222A, and are probably some other part (such as an MPS2222) which have a lower current rating.

ErnieHorning
09-12-2012, 01:26 PM
For two pennies a piece...
Who knows what you’re going to get? They provided a nice, high resolution picture that you can even zoom in closer to but it’s of a 2N2907A transistor.

The bi-polar transistors have a larger voltage drop and waste a little more power than the FET’s. You’ll still want the opto for isolation though.

LightUp
09-12-2012, 01:54 PM
Another possible issue is whether the base drive current will ensure full Ic current with a low collector-to-emitter voltage (Vce_sat). Verify that the new part's specs are equal to or better than the original designed part.

I can recall a past job project where many newly assembled boards (of a MODEM) failed due to the 12V relay not getting its full 12V across the coil. Turned out that the metal case 2N2222A relay driver was replaced by a plastic version (-cheaper-) which had a lower current gain (Hfe). Hence the transistor's Vce was around 6V, preventing the relay contacts from closing properly. Replacing the plastic version with the 2N2222A solved the production problem.