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Re: Show and Tell - New user S100 system up & running (well sorta !)

Hi Philippe,
Good to hear that you got your case parts sorted out.
To answer you question regarding power supplies, I wouldn't bother getting a second 15v power supply to generate the -15v rail unless you plan to use some vintage S-100 cards, I think some early memory board used it ???
When I put my system together I just worked from the standard S-100 linear power supply specs shown in a picture on the S100 Computers site (I think), although it's wired up in my system none of my cards draw any current from it. In fact I can't think of a S100 computers card that used the 15V rail either but I'll leave it in my system as I have an idea for a S100 card that may use it.
You are correct in your assumption of wiring up the power supplies, each power supplies output is fully isolated so you are free to connect either the negative or positive terminal to chassis ground as required to generate negative or positive outputs with resect to ground, the outer metal casework of the power supply will be connected to the mains earth connection.
If you message me off board I'll send you a sketch of my setup
David Fry

On Friday, May 30, 2014 9:49:57 PM UTC+1, Philippe Elie wrote:

I just received the Modushop parts in perfect shape, I sent an email stating my issues with their website, I got an answer instantly and received the parts two days later.. .very happy with the service and the quality of the product :)

David, I have a question for you, your feedback would be very appreciated : I received and tested the switched power supplies from mouser, all is fine except the fact that I naively thought the PS output both positive and negative voltages vs the GND output... this is not the case obviously, the DC outputs at +V and -V connections. which means I have to order another LS50-15 to generate the other +-15V line :( hence my question :
- the pictures of your PSU show that, apart from the large 7.5V PS, one of the two others is slightly bigger, while I would expect to see two similar LS50-15 there, is there a reason for that ?
- assuming I have a total of 2xLS50-15 and one Meanwell RSP200-7.5, I understand I have to wire +V of LS50 #1, -V of LS50 #2 and -V of RSP200 together to the GND (which is also connected to the mains ground), to get the +15, -15 and +8V. Is that right ?

Sounds like this sounds like a dubd question, but I'd like your confirmation there.. my next step will be try the Ithaca Z80 CPU board I just received to get me up to speed before I solder my CPU board myself. I received the Openbench Logic Sniffer, this is a really wonderful tool for $50 !

thanks a lot in advance for your reply

kind regards,