RE: Exploring the Recom RH-2405D

jw0752 — Sun, 11 Nov 2018 06:16:36 GMT

Tonight I continued my experiment to put the RH-2405 on the Linear power supply board in place of the boards original circuitry. I ran into a couple of problems but they were related to not being careful enough. For example I had chosen a 330 uF cap to go across the supply line to the RH-2405 without looking closely at its voltage rating. I am at least cautious when I power up my experiments and so I was monitoring the current supply to the board as I brought the voltage up. After about 18 volts the current began to climb rapidly reaching a couple amps when there should have been no more than 200 mA on the idling power supply board. I quickly backed it off and inspected everything before I tried again and found the same problem. At one point I happened to touch the 330 uF cap and found it was getting warm. Come to find out it was rated at 16 volts and was breaking down as I pushed the voltage past its tolerance. This mistake caused no further damage and was rectified with the replacement to a 50 volt cap. I am not going to discuss the second glitch but suffice it to say it was a foolish mistake. Still no damage and so I lucked out tonight John (3) Smoke and Fire (0).

Here is what the PS board looks like after I mounted the RH-2405 and rerouted the board connections. When I perform these Frankenstein procedures I like to use as much of the original traces and pads as possible to integrate the new circuitry. I have also included a couple pictures of the original board layout so you can compare.

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Modified Board

[View:/resized-image/__size/620x465/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-f2e11cc7-0e37-4dbc-a565-a79fa1270485/2816.contentimage_5F00_189121.jpg:620:465][View:/resized-image/__size/620x465/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-f2e11cc7-0e37-4dbc-a565-a79fa1270485/5140.contentimage_5F00_189122.jpg:620:465]

Original Board Layout

With this experiment completed I will continue working on the application for this circuit board.

John

RE: Exploring the Recom RH-2405D

Jan Cumps — Sat, 10 Nov 2018 11:38:38 GMT

In our electronic load, we use a LM2662LM2662. It's cheaper and doesn't need an external inductor.

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edit: the unit of the inductor in your schematic is uF. Shouldn’t it be uH?

edit2: does the fan need regulated voltage? Could you tap that one off before the regulator? Asking because it will cause most of the heat in the regulator. If the 28 V is too high for the fan, a few diodes in series can drop the voltage.