Hardware Hobbyists vs. Emulator Jockeys

Dave McGuire mcguire at neurotica.com
Wed Jun 17 17:47:28 CDT 2009

On Jun 17, 2009, at 6:26 PM, Eric Smith wrote:
>>   While I agree with you here, I have to admit that, if my  
>> PDP-11/70 had switching power supplies, I'd probably run it a lot  
>> more often.  I'd *never* make it an irreversible modification,  
>> though.
> Unless you've already replaced them with something else, your  
> PDP-11/70 *DOES* have switching power supplies!

   I'm looking at the schematic for the H744, and I see an LM723 with  
a big fat 2N5302 (Ic=30A) wrapped around it.  Now, I'm aware that the  
LM723 can be used in a switching regulator topology, but at first  
glance that's not what it looks like to me.

   I'm somewhat embarrassed to admit that, because I've repaired  
probably a dozen H744/H7441 regulators, including one just a few  
weeks ago in my newly-acquired PDP-11/50.

   So...are you certain?


Dave McGuire
Port Charlotte, FL

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