Power Designs D‑series display board update

After the acqui­si­tion of my Power Designs 5015D pow­er sup­ply, I real­ly want­ed to upgrade the dis­play mod­ule so that I had an extra dig­it of res­o­lu­tion. I already had a few ADC/LED meter boards left over from pre­vi­ous projects, but need­ed a dis­play board to pair with it.

Power Designs D‑series dis­play board Rev. 2.4

While the orig­i­nal “OTE 2020” dis­play boards worked fine with the new ADC/LED Rev. 2.0 dri­ver boards, I want­ed to update the design to uti­lize the spe­cif­ic foot­print for the dis­play mod­ules, and increase the trace widths to bet­ter match the dri­ver board.

Display board Rev. 2.4 top bare board

The Lumex Opto LDS-C416RI 7 seg­ment LED dis­plays use a stan­dard 14 pin DIP lay­out, but only uti­lize 10 pins. Using the 10 pin foot­print allows for eas­i­er rout­ing of traces, and the abil­i­ty to use big­ger cir­cuit traces. I also slight­ly raised the height of the LED’s to bet­ter uti­lize the front pan­el dis­play open­ing and view­ing angle.

Display board with 7 seg­ment and dis­crete LED’s fitted

After pair­ing up the dis­play and dri­ver board, it was time to tack­le mod­i­fy­ing the 5015D from a 200 mV dis­play out­put to a 2.00 Volt full scale out­put. I used the schemat­ic for the TW5005D pow­er sup­ply as a start­ing point, as it has a sim­i­lar lay­out and meter cir­cuit com­pared to the 5015D.

Display board fit­ted with ADC/LED dri­ver board installed in 5015D

The out­put of the Volts and Current meter­ing cir­cuits are com­prised of a sim­ple volt­age divider with a trim­mer resis­tor for cal­i­bra­tion. By chang­ing one resis­tor in each divider cir­cuit the out­put can be changed by a fac­tor of 10 to increase the ratio to 2.00 volts full scale.

Location of changed com­po­nents for 2.00 volts full scale modification

While I was mak­ing changes to the cir­cuit, I also changed out both of the trim­mer poten­tiome­ters to a Bourns 3299Y‑1–101LF 100 Ohm 0.5W PC pin 25 turn units. This allows for a fin­er adjust­ment than the orig­i­nal sin­gle turn trim­mers. R43 in the cur­rent cir­cuit was changed from a 15 Ohm to a 158 Ohm 1% resis­tor. R11 in the volt­age cir­cuit was changed from a 174 Ohm to a 1.7K Ohm 0.1% resis­tor CMF551K7000BHR6.
Calibration was fair­ly straight­for­ward, by set­ting the out­put volt­age to 50 volts with a cal­i­brat­ed volt­meter con­nect­ed and adjust­ing R10 V CAL trim­mer until the meter match­es the exter­nal volt­meter. For cur­rent cal­i­bra­tion I con­nect­ed a cal­i­brat­ed DC amp meter capa­ble of at least 3 Amps, and an 8 Ohm 50 watt load resis­tor and set the out­put for a 1.5 amp read­ing on the exter­nal amp meter. I then adjust­ed R14 I CAL trim­mer until the front pan­el meter matched the exter­nal amp meter.
Warning, do not leave the cur­rent out­put at 1.5 Amps for very long as the resis­tor will be dis­si­pat­ing 18 watts and will heat up quickly.

Power Designs 5015D with updat­ed meter display

My col­lec­tion of Power Design sup­plies has grown over the past few years, but I still use most of them. Probably the least used is the 6150 as I infre­quent­ly need that much pow­er for most of my projects.

Power Designs, Inc. pow­er sup­ply col­lec­tion 2022

Eagle CAD V7.7 board and schemat­ic ZIP file for Rev. 2.4 meter dis­play board

Eagle CAD V7.7 board and schemat­ic ZIP file for Rev. 2.2 ADC/LED dri­ver board

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