Clearance - 30v 3A TENMA PSU

Thanks for the info!

That looks useful, and I could do with a small linear supply.. it's got fairly accurate readback capability it seems, and also the supply is programmable..

I could not resist at that price, so I have ordered one.

I have succumbed too. After all, it was my birthday last week (honestly). When I first looked, there were only two in stock, so I thought I'd better get a shift on!

I have succumbed too. After all, it was my birthday last week (honestly). When I first looked, there were only two in stock, so I thought I'd better get a shift on!

Happy Birthday Steve

Rod

Thanks!

Hi Steve,

Happy Birthday!

Also, the supply arrived this morning, so hopefully you'll have got yours today too. I won't get a chance to try it out properly until tonight or later in the week, but I did switch it on and try it for five minutes..

it's all-steel construction with a plastic front panel, very heavy since it's got the transformer, and you can hear the relays clicking through the ranges. The user interface, since it has just 2 rotary knobs with buttons, is ok-ish, I've seen a lot worse! but it will be interesting to see what you think of it too. At first glance there's a few typos and mistakes in the manual, but nothing we cannot figure out I'm sure!

Thanks!

I hesitated before ordering and missed the cut-off, so mine won't arrive today. I'm glad there is a manual (even with typos and mistakes). I wasn't sure if there would be. My power supply needs are fairly simple, so I'm sure it will do me nicely, but I'm looking forward to not having to hunt around for a suitable power supply when I get a new gizmo!

Mine came today .

First impressions are favourable, although I would have appreciated a longer mains lead. As I don't actually have a bench, my power sockets are not just above the bench (I have a desk with sockets in the skirting board), so I can't blame them. It's only a "kettle lead" so easily rectified (no pun intended).

Just a slight hum from the transformer.

It's a bit retro to be provided with an actual CD nowadays. No instructions or manual for the software (imaginatively entitled "72-2705") but seems straightforward.The USB driver installed automatically on one of my Windows 10 PCs, but another of my PCs doesn't like the USB device at all. However, that was also easily rectified as I used one of those cheap CH340 Serial-USB converters. I have an actual serial port on that PC, so I need to dig out a proper serial to serial cable for it (assuming I didn't chuck them all away).

[edit] After installing the software and playing with it via the serial-USB adapter, my PC mysteriously decided to recognise the Tenma's USB port, so all is good now!

Hi Steve,

Oh excellent, that's great to hear it functions on Windows 10.. I will try to upload the CD to the cloud somewhere, since I'm bound to lose it!

Hi Steve,

Hehe I had the same issue, the supplied kettle-lead is too short : )

I've backed-up the user manual and CD contents, in case we ever lose them.

My PC (running Windows 10) didn't seem to need the driver, is used the default usbser.sys automatically.

Also, for Linux, plugging the USB connector into a Pi caused a /dev/ttyACM0 to appear, so that's working fine too.

I tried a few commands and it gave the right responses! It's reporting back V2.5 firmware, although the user manual mentions V2.0.

The only slight issue is that (like other) SCPI instruments, it's a wild west and linefeeds are sometimes not implemented as they should be, with some instruments wanting carriage-returns too, and so on.

In the case of this device, it seems to not want the control character, and it ignores them which I can live with, but the responses contain no linefeed either : ( That means either a delay needs to be implemented, or characters counted/parsed as they arrive. Anyway, since this is a simple device, it can be easily worked around - the numbers are formatted, so won't be variable-length.

In summary, the programmable capability is usable, so we can write simple code to do stuff if desired!

This code is working for me on the pi.. (first type pip install pyserial ):

#!/usr/bin/python
####################################
# PSU test
####################################
# definitions
import sys
import serial

# main program
if (len(sys.argv)>1):
  psu=serial.Serial(sys.argv[1], 9600, timeout=1)
else:
  psu=serial.Serial('/dev/ttyACM0', 9600, timeout=1)

print "writing.."
psu.write(b'*IDN?')
print "reading.."
resp=psu.read(64);
print "result is "+resp+" length is "+str(len(resp))

I've not connected up the PSU output to any equipment yet, but just playing around with the UI, I'm happy with that aspect! There's two UI modes, I set mode 2 (press both rotary buttons for about 1 second to toggle between them, although the manual says 3 seconds) and to me that's more usable. If I ever get around to opening the supply, it would be nice to perhaps change out the lower red LEDs to a different color, so that red is only for CC/CV LEDs, to more easily see at a glance if the output is on, by looking for the presence of red.

It's also cool that 'electronic fuse' capability can be enabled if desired, aka 'over current protection' mode, i.e. rather than transition to CC mode, just cut out the output if the set current is exceeded. that's really nice to have, my old PSU is missing that.

Thanks 14rhb for spotting this supply, it's looking promising... If it's good once tested I hope to buy another to get dual-rail capability.

Yay! Found a couple of nice long kettle leads AND a long RS232 serial cable (male DB9 to female DB9) in the garage. Frees up a USB port and no annoying USB driver issues to contend with. I have the same V2.5 firmware as you (not surprisingly).