Recently came across one of those units on sale so I thought I would grab one. The version I got had
DL24E-a on the silkscreen and shares the familiar 4-FET configuration with transistors marked as
IRFP264.
![Cheezeball DC Load: DL24P: Pump, or Dump ??? 2086097-0](https://www.eevblog.com/forum/index.php?action=dlattach;topic=254428.0;attach=2086100;image)
Having read about the gate control voltage horrors, I decided to probe mine. I am using my cheapy $20 pocket oscilloscope, so the readings I got are to be taken with a grain of salt, but I find that it tends to perform OK at the time bases we are dealing with here.
So first of all, there does appear to be a slight ramp up time when the load is switched on as the gate control voltage softly rises over 4-5 ms. No glitches, no ringing, the current rises and just stays there, so they at least appear to have addressed this issue?
![Cheezeball DC Load: DL24P: Pump, or Dump ??? 2086103-1](https://www.eevblog.com/forum/index.php?action=dlattach;topic=254428.0;attach=2086106;image)
Rather predictably though, if I start current limiting my 150W 30V power supply I was testing this unit with, the whole system would start oscillating wildly with gate voltages jumping as high as 12V before the cycle would repeat again. Curiously enough, after a few seconds of jumping like this, the load appears to give up and disable itself, even though the display still showing ON. It's worth noting that 12V is the actual supply voltage from the dinky power adapter they include so it would appear to be the maximum they drive the MOSFETs with.
Another surprise came when I was selecting different modes with the load off and still connected to the power supply. I heard clicking noises from my PSU which it usually makes when there are sudden current spikes and sure enough: even when the load is off, changing the modes causes a glitch on the gate, opening the transistor fully for a few milliseconds before reining it back in. Sometimes those glitches are just a couple spikes, lasting less than a millisecond, but still a lesson learned: best to disconnect the load completely when changing modes!
![Cheezeball DC Load: DL24P: Pump, or Dump ??? 2086091-2](https://www.eevblog.com/forum/index.php?action=dlattach;topic=254428.0;attach=2086094;image)
![Cheezeball DC Load: DL24P: Pump, or Dump ??? 2086085-3](https://www.eevblog.com/forum/index.php?action=dlattach;topic=254428.0;attach=2086088;image)