I haven't used a bench power supply with current limiter for 34 years. I have a quick question.. The current display, is it an ammeter? Or does it just display what the current limit is set to? Or both?
Thanks.

 

hi Rich,
Most ammeters these days are digital displays, they display the actual current drawn by the Load.
Is this what you are asking.?
E

 

hi Rich,
Most ammeters these days are digital displays, they display the actual current drawn by the Load.
Is this what you are asking.?
E

Yes, thanks that's a handy feature then. I'm always faffing about connecting the multimeter in series. I'm looking at some on ebay.

 

On the supply I use most frequently, the current display displays limit value or actual current; it depends on the setting.

 

On mine, pushing in on the current adjustment knob switches the (4 digits w/ floating decimal for mAs) current readout to the set limit mode for a brief period to allow setting the limit, then times out and reverts back to actual current display mode. Depending on what I am doing (typically <10V) I set it around 20-200 mA. It becomes obvious I have hit the current limit when the voltage readout drops below what I have it set for as it starts reducing V to limit A. On eBay I would recommend the KORAD KD3005D - Precision Variable Adjustable 30V, 5A DC Linear Power Supply. Adjustable to .0IV and .001A to give displays of 00.01V and 0.001A and up to its limit. I have 2 of these and am very satisfied with them. A good solid linear power supply. They also make them with a more expensive digital front end with memories and such that I don't need for a higher price.

 

Depending on how critical your current measurement needs to be, some are more accurate than others. If you just need a ballpark then most are probably fine, but if you need to know down to the mA or uA range then do your research. Ditto for voltage. I'm using the Rigol DP832 and it seems to be fine for most things I've used it for. Some of the features I use a lot are voltage and current protection. On the lower end power supplies you can set a current (and/or voltage) limit and it won't exceed that, but it will keep chugging at that level until you turn it off. i.e. you set it for 0.1A output and short something, it will keep giving you 0.1A until you turn it off. On higher end models you can optionally set a trigger current (and/or voltage) that makes it instantly turn that channel off completely. So if I think a circuit should only require 0.1A at worst, I set the trigger at 0.1A. Now if it draws 0.1A or more that channel instantly turns off, potentially saving your parts. It's got a lot of other features as well that may or may not be useful to you, depending on what you're doing, I'm sure competing products by other brands have similar features.

 

The current display, is it an ammeter? Or does it just display what the current limit is set to? Or both?

Depending on your make/model, it's likely both: when powering a load, it displays the current being drawn; when adjusting the current limit setting, it displays the setting.

 

On the supply I use most frequently, the current display displays limit value or actual current; it depends on the setting.

Mine also, I built it about 30+ years ago, but lost the design schematic for it some time ago in a move.
Max.

 

I use a "GOPHERT" as bench PSU. You can set the maximum output current. It will not switch off the power once over the maximum current, but it will lower the output voltage. I can't call it SUPER PSU (stabilisation is fine, but the ripple could be less)and I won't use it if e.g. my stay on Mars would depend on it... One minus : the output connectors are at the back of the box...
For measuring currents (ac AND dc !) I use a "UNI-T UT210E". It is small, but most important : it measures as wel AC as DC currents and it is CHEAP. (about $70 at Amazon) It has 3 1/2 digits and measures from 1mA to 200A. Again : I would not use it if my stay on Mars would depend on it... but for everyday measuring it is just great ! A minus for this meter is that you have to "zero" it mannually after every measurement, but (for that price) I don't mind.

 

I use a "GOPHERT" as bench PSU. You can set the maximum output current. It will not switch off the power once over the maximum current, but it will lower the output voltage. I can't call it SUPER PSU (stabilisation is fine, but the ripple could be less)and I won't use it if e.g. my stay on Mars would depend on it... One minus : the output connectors are at the back of the box...
For measuring currents (ac AND dc !) I use a "UNI-T UT210E". It is small, but most important : it measures as wel AC as DC currents and it is CHEAP. (about $70 at Amazon) It has 3 1/2 digits and measures from 1mA to 200A. Again : I would not use it if my stay on Mars would depend on it... but for everyday measuring it is just great ! A minus for this meter is that you have to "zero" it mannually after every measurement, but (for that price) I don't mind.

Yeah think that uni-t is the same as mine, another slight niggle is it defaults to AC current when you've been off the scale and back to it. I do like it though, it's nice and small (thumbs up emoji)
My emojis are greyed out

Edit: sorted