What would it take...

Philip Pemberton classiccmp at philpem.me.uk
Fri Dec 8 02:45:42 CST 2006

Ethan Dicks wrote:
> On 12/8/06, Lee Davison <lee at geekdot.com> wrote:
>> There are no excuses .. http://www.geocities.com/mwinterhoff/galblast.htm
> Very nice.  I may have to look into that as a replacement for my ancient 
> UP600a.
> I'd personally look into taking the path of an external bench +24VDC
> supply, but I can see how it'd be handy to have it all self-contained.
> Has anyone on the list built that one?

Yep: <http://www.philpem.me.uk/elec/galblast/>

Mine's based on a variant of the design that was slightly cheaper to build. 
74HC573 latch, resistor-ladder DAC, opamp, KA34063 (=MC34063) based switching 
PSU, a pair of 7407 O/C buffers, a 7805, some resistor packs and a few passives.

The one thing I am going to do is replace the diode voltage dropper with a 
proper 3.3V regulator - should be an easy mod (steal GND from the 7805, Vin 
from the top of the diode chain, Vout to the bottom of the chain).

Since taking that photo, I've added a proper DC power jack and a slightly 
beefier power switching transistor.

My 6502 computer (<http://www.philpem.me.uk/elec/6502/>), incidentally, is 
stuffed full of GALs. One for each board at the moment, two on the IDE/FDD 
controller (which is being redesigned to use a Xilinx CPLD).

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