FS-1 power options

dingebre · Posted: Sun Apr 05, 2009 8:19 pm Post subject: FS-1 power options

I've scrutinized Dave Brown's build page and the JH pages, schematics, etc. but I'm a little stumped.

I am running FracRack format with Blacet +/- 15 volt power supplies. I note that on all my Blacet modules there are additional power conditioning components; a couple of 0.1 ceramic, a couple of 100 uF electrolytics, and a couple of 1n4001 diodes.

Dave Brown took out all the 18 to 15 vdc power supply circuitry but left in C3,4 (and C5,6?) for his MOTM version.

If I do the same as Dave Brown, will I be OK, or should I do something more like the Blacet filtering?

David

b-funk · Joined: Jul 17, 2007 Posts: 193 Location: Berlin

David,

if you use a good regulated psu there should be no problem if you leave off the extra filtering. I don't know the Blacet psu, but I just read positive things about Blacet stuff, so you should do fine following Daves approach. On the other hand, some extra filtering doesn't hurt.

Best wishes,

Tobias.

dingebre · Posted: Mon Apr 06, 2009 2:34 am Post subject:

Thanks Tobias.

David

sduck · Posted: Mon Apr 06, 2009 1:28 pm Post subject:

You might want to send Dave a email about this. I had some concerns also, which he was able to alleviate. The concern he had was that the 2 sets of caps at the power input might cause some startup problems with a psu that was near it's limits. I don't have the details handy, but he can explain them to you if you're curious.

davebr · Joined: Jun 09, 2007 Posts: 198 Location: portland, or

The next time I have the board out I will probably remove C3/C4. I wanted them next to the power connector and didn't realize that there are three sets of capacitors all in parallel. This puts 54 uF on the power connector which really isn't a lot more than two 1U modules in the same space. However, it's not necessary either. The electronics on PCB2 are filtered with C9/C10. The electronics on PCB1 are filtered with C7/C8 and C1/C2. This drops the capacitance to 32 uF. I'm not even sure that C7/C8 are necessary.