HP E3630a uses

[Matthematik]

I have wanted one for a while and finally picked one up on eBay. Well, the display doesn't work so I'm going to return it but I also noticed it doesn't have the ten turn pots that my E3610A has. It also doesn't have the ability to set a maximum current. For these reasons it seems to me, a newbie, that it isn't really suitable for the basic prototyping that I tend to do. It seems like it would be a real pain trying to get the exact voltage you want and really unforgiving to an inexperienced hobbyist. I would just like to get everyone's thoughts on this power supply. What sort of applications does it have? Is the ability to fine tune your voltage not always necessary?

[nfmax]

I like my E3630A, but it is only one of a stable of bench power supplies. The advantage of a triple supply is that you can turn all three supplies off and on together, and being an HPAK design they won't do stupid glitchy things while coming up & going down. They have a common 'ground' terminal which makes wiring up to the UUT easier. I find the adjustability is OK, but then I'm not going to be using this as a substitute adjustable precision voltage source. The fixed current limiting means that I probably won't be using it for 'first power' applied to a new & untested circuit containing expensive and vulnerable parts, but really the ~0.6A limit on the ±20V supplies is pretty safe for most things. The compact size is also nice.
Most recently I have been using it to simulate a 12V lead-acid battery while developing a battery protection circuit, and the adjustability was fine for playing around with the turn-off & on thresholds (about 11.0V and 12.3V). Its real sweet spot is powering up little the development boards/modules that are known to work but don't come with a PSU. It would be perfectly OK as a beginer's first PSU though.
If the display doesn't turn on at all, before sending it back, open it up and check that the cable from J1 on the main PWA (next to the meter control pushbuttons) to the display module is correctly plugged in at both ends. It may just be there is no 5V reaching the meters.

[TheSteve]

When I first got my 3630 I was a little disappointed it didn't include the 10 turn pots. The non-adjustable current limiting has never really been an issue for me though. The power supply was designed to provide 5 volts for logic and positive/negative for opamps etc. When it was released there would have been a big demand for such a supply. It isn't hard to get the supplies adjusted - but it isn't a precision power supply. I don't think I'd pay the money people on ebay often ask but if you wait long enough they pop up for around 100 dollars now and then - at that price they are great.
They are also very easy to service like the 3610 and 3620 which is a plus.

[Matthematik]

Thanks for the responses, they were really helpful in giving me an idea of how I can use this thing. I wonder if I can add ten turn pots or if the design prevents it.

Regarding my display not working, it turns on but stays at 0 Volts. I just opened it up and there doesn't appear to be anything obviously out of whack. It seems like a decent opportunity to get my feet wet with repairing electronics. I think I'll keep it if I can get the seller to come down on the price.

[3141592]

What sort of applications does it have? Is the ability to fine tune your voltage not always necessary?

Precise voltages aren't at all necessary in most cases, where all you need is a simple, reliable supply. Heck, if you could only adjust it by volts, it would still be good enough for most things. Reliability and low noise are more important in my opinion, than it's resolution... but obviously, it all depends on what you plan to do with it.

[bitseeker]

Thanks for the responses, they were really helpful in giving me an idea of how I can use this thing. I wonder if I can add ten turn pots or if the design prevents it.

You can certainly replace it. Just get a 10-turn of the same resistance. The values are on the back of the pots. Just be aware that they aren't cheap, unless they're knockoffs. The knockoffs work, but require more torque to rotate (at least the one I've tried did). How long they'll last, I don't know (get what you pay for, etc., likely applies).

Regarding my display not working, it turns on but stays at 0 Volts. I just opened it up and there doesn't appear to be anything obviously out of whack. It seems like a decent opportunity to get my feet wet with repairing electronics. I think I'll keep it if I can get the seller to come down on the price.

If the voltage display doesn't change, it might be a bad connection or problem with the sense circuitry.

As for lacking adjustable current limiting, yes it's unfortunate, but usually not an issue for general use. The high-current channel does have short-circuit protection to limit the current to around 1A, so you won't get all 2.5A in that scenario.

[_Wim_]

What sort of applications does it have? Is the ability to fine tune your voltage not always necessary?

Precise voltages aren't at all necessary in most cases, where all you need is a simple, reliable supply. Heck, if you could only adjust it by volts, it would still be good enough for most things. Reliability and low noise are more important in my opinion, than it's resolution... but obviously, it all depends on what you plan to do with it.

I agree, but when messing around, I find being able to set current limiting very useful. Most of the time you only need maybe 100mA, and by setting the limit only a little higher, it gives you reasonable protection when something goes wrong. A supply without limiting should preferably only be used for powering "known" good circuits.

[nfmax]

The E3630A does have current limiting (on the ±20V outputs), it's just not adjustable:

0 to ±20 V Outputs: Maximum rated output current is 0.5 A. Short circuit output current is 0.55 A ± 5% and a fixed current limit circuit limits the output of each supply to this maximum at any output voltage setting. Unbalanced loads within current rating are permitted.

The 6V output has foldback limiting:

0 to +6 V Output: Maximum rated output current is 2.5 A at 6 V. The maximum available output current decreases with the output voltage setting. A current foldback circuit limits the output to 2.75 A ± 5% at 6 volts and, with decreasing voltage, reduces the current limit linearly to 1 A ± 15% at zero volts (short circuited).