Products > Test Equipment
Tenma 72-8695 2 x 32v 3A + 5V @ 2A mini-review / teardown
T4P:
Yeah but these modern cheap shit are not worth at all trying to get more accuracy, if it suddenly "decouples" the PSU
My 80's "cheap shit" supposedly is a thousand times better than current cheap shit
Digsys has my PSU too, just labelled 5A (mine does 4.31Amps at 30V even labelled as 3amps, go figure!)
mariush:
Maybe I wasn't too clear... by decoupling I mean the relay inside disconnects so that side of the power supply is outputting 0v when I turn the pot all the way to lowest value.
It sort of makes sense to me, if I adjust it to 0 A, you wouldn't get anything out, right? So why keep the relay enabled?
10$ for a 5-10 turn pot doesn't seem too much extra if I'd be able to adjust by 0.05 A instead of 0.2-0.4 A jumps.
T4P:
--- Quote from: mariush on September 27, 2012, 05:25:10 am ---Maybe I wasn't too clear... by decoupling I mean the relay inside disconnects so that side of the power supply is outputting 0v when I turn the pot all the way to lowest value.
It sort of makes sense to me, if I adjust it to 0 A, you wouldn't get anything out, right? So why keep the relay enabled?
10$ for a 5-10 turn pot doesn't seem too much extra if I'd be able to adjust by 0.05 A instead of 0.2-0.4 A jumps.
--- End quote ---
Oh. In my PSU the relay is only for tap switching, i thought you meant your relay decouples the PSU below 80mA, i was gonna replace the pots in mine, it's getting very jumpy and it's one-turn after all, maybe change all of them to ten turn pots so i get extremely fine adjustment :D
Daz:
Hi, I know this is a fairly old topic but as somebody looking into buying their first bench PSU I'd really like to understand something:
The 5v 2amp channel of this PSU (channel 3) has its negative terminal connected to chassis earth (the manual for this PSU that I found online also confirms this). As an electronics newbie, my understanding is that I can't use an oscilloscope on a circuit that has a mains earth connection. Is that correct? If so, then I guess the 5v 2A channel would be useless to me if I needed to use a scope on my circuit?
If all of the above is correct then it's a bit annoying that this PSU has the 5v terminals marked as red and black, the same as the floating outputs on channels 1 and 2. I guess they should really be red and green to signify positive and ground.
Do all the other brands of cheap 3 channel PSUs have a similar channel 3 setup, i.e. using 5v and earth?
Thanks,
Daz.
mariush:
Technically, you could just plug the power supply in a socket that has no ground lead. Practically, you shouldn't.
You could also just buy a couple of heatsinks (they're about 2-3$ each),
http://uk.farnell.com/multicomp/mc33279/heatsink-to220-x-2-7-1-c-w/dp/1710624
http://uk.farnell.com/jsp/search/productdetail.jsp?sku=1710623
http://uk.farnell.com/abl-heatsinks/ls85/heat-sink-to-220-to-3p-7-1-c-w/dp/595810
http://uk.farnell.com/jsp/search/productdetail.jsp?sku=1703170
unscrew the regulators from the case, screw heatsinks on the regulators and then have the regulators sit on something that's not grounded. (Ex. get a small square of prototyping board, drill some holes on the corners of the protoboard and use some nylon spacers or something, solder the regulators on the protoboard.)
The case isn't sealed with anything, so you won't void any warranty doing this.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version