Not sure I would call myself the master, I have just been using these drives for a long time. More like a pack rat when it comes to saving everything I can find about them. I think I have only seen one 78xx regulator short, but I still group the outputs of good switching supplies right up there with the reliability of 78xx regulators and I am quite confident that I’ll not see an over-voltage. I’m still thinking of adding the “crowbar” circuit to my computers with these supplies to further safeguard their operation and protect my antique computer boards. I’m still searching for the schematic… The Meanwell QP-200F outputs +5, +15, -15 and +24V. I only bypass the 5V regulator on my boards, as the +15 and -15 are adequate to operate any 7812 or 7912 type regulators. Bob Bell From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Crusty OMO Hi Bob, From: bbel...@gmail.com A “glitch” on any power supply is a possibility. Even 78xx type regulators could short and put the full input voltage on the output. I am confident that the 5V output on the Meanwell QP-200F is no more susceptible to overvoltage than the on-card regulators. Nevertheless, John has a good point. Years ago, I had designed a simple (as in 3 or 4 components) crowbar circuit that protected the circuitry on the output of a power supply. If the voltage rose higher than a set threshold, the crowbar would trigger and short the supply output to ground. In those days, the short would blow a fuse. If I put this circuit on the output of the Meanwell, the short should safely shut down the supply and prevent damage to the 5V circuits. I’ll need to lookup references to this circuit, and would be glad to publish it if anyone has an interest. Bob Bell From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of John Monahan On S100 bus power supplies, unless you are extremely energy conscious it’s easier to supply S100 bus motherboards with 8V and 16V switching power supplies rather than 5V & 12V and pulling each and every voltage regulator on every S100 board. A suggested source is here:- http://s100computers.com/My%20System%20Pages/The%20Box/The%20Box.htm#The_Power_Supply there are countless others. I would also be careful getting a “cheap” 5V unit. If the is a glitch to a higher voltage, there goes each and every board in your S100 box if you don’t have a V regulator on each board. John From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of J. Alexander Jacocks I have noticed several folks are using the Meanwell QP-200F PSU, recently. I looked it up, and it is a bit expensive, but it appears to be much smaller than my current 8/16vdc pair of units. I assume that the unit can be adjusted for the proper voltages? Do folks who have them think they're worth the money? Thanks! - Alex -- --
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