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Homemade electronics Stuff old and new
DC powerload, electronic load, Monster Sized 0-100V 0-500A watercooled 2002

This DC powerload is made at work.. so it is not fair to call it homemade, very different budget was involved,
Also all mecanics, welding, plumbing, pumps, heat exchanger, was done by a coworker, all i did was the electronics :-)
Lets try to explain : 10 main sections, 80 x 40 x 3 cm water cooled aluminium plates
Each of the 10 consist of 6 x 28 TO220 fets = 1680 FETS !!
one controller PCB handle 28 fets, in a banked constant current digital set/select system
so this means there are 60 controller PCB's connected to a parallel digital bus
since each pcb got 4 bits of current adjust and enable, the total current resolution / range was amazing
also this banked solution was clearly the way to make it stable.

Total current was limited by this current sense resistor, to 500A
Digital set current was 10A max pr pcb = 600A
4 bits pr PCB = 625mA LSB resolution.

28 x 3 fets on each side.

Erly bring-up stage, lets see hos one module behave

Heat exchanger is hard to see on the very left

better view of heat exchanger, amazing how small they are

how to make 500A for testing ? just alot of car starter batteries.
This was the very start, later we added a few pallets more,
also the wheels on this table broke down from the weight

on the erly bringup tests, I added 3 x 10A PTC fuses on each battery like this
just in case we have a short or other brakedown,
this will limit the current to a nice safe level of only 30A x 16 = 480A

An erly version of the controller PCB, the initial design only used 10 fets pr pcb
funny how rendering 3D from a 20 year old PCB file create a bit errors :-)


OZ2CPU 2002