Hello all

Just bought a GOPHERT CPS-3205 II Portable Power Supply to use with my breadboard projects.
The "User Manual" is a piece of A4 paper folded in half. Tells you what the features are and nothing else.
So I am looking to connect with anyone who has this unit who can explain something to me.
In particular CC mode. Which is Constant Current mode. How it works.

Anyone familiar with this unit?

Thanks.

 

hi,
Lots of info on line.

E

 

Hello,

And the "manual"

Bertus

 

hi,
Lots of info on line.

E

Yes. I know.I have watched it. Some of it is great. Especially VoltLog's 42 minute review which is pretty positive. None of it answers my question. That's why I came here.

 

Hello,

And the "manual"

Bertus

Thanks for that but I have that one too. Found it last night. The manual that came with the unit was the folded A4 sheet.
It doesn't answer my question. So i am looking to connect with someone who has practical experience in using it.

 

Here is the issue.

There are Constant Voltage and Constant Current indicator LEDs.

The 6 page PDF on page 2 refers to Turn ON/OFF : Turn ON - Constant voltage state for both.

Just reading that suggests that there is some physical way of setting this state ON or OFF.

But there doesn't apear to be and nor does the manual say that there is.

I am also aware that this document was created in China so something may have been lost in translatiion.

So I am looking for an explanation of how this CC mode is set and what it actually means.

I can imagine a scenario where I might want a steady current output, say 500mA, for some
particular purpose and it would be useful to have a device that could deliver that without me
messing about with resistors.

From the fact that you can physically set the current output, as well as the voltage, it would
suggest that this is possible. Otherwise why would the current be independently adjustable?

But I have been tinkering with this unit now for a couple of days and I can't get it to output
the current that I set it to.

Bottom line is that I am trying to decide whether the unit is faulty or not or whether I have
just not figured out the right procedure.

Hence the desire to collaborate.

 

Hello all

Just bought a GOPHERT CPS-3205 II Portable Power Supply to use with my breadboard projects.
The "User Manual" is a piece of A4 paper folded in half. Tells you what the features are and nothing else.
So I am looking to connect with anyone who has this unit who can explain something to me.
In particular CC mode. Which is Constant Current mode. How it works.

Anyone familiar with this unit?

Thanks.

To set Current, push select switch to A, and set output with rotary potentiometer, connect load and it will give the Constant Current, the voltage will vary according to the resistance of the load to maintain the desired current.

 

The constant current limiter function (as opposed to a foldback current limiter) does as it's name implies i.e. will limit the current drawn by your circuit to some constant value. If the load tries to draw more than that current, the voltage will drop.

Two things I use CC limit are:

Setting it to some value a bit above the maximum expected for the circuit under test. That way inadvertent short circuits will be limited to that value protecting the circuit, probes, electrolytics, etc. If a capacitor is in backwards, the CC light turns on. That's better than the cap exploding

Also useful when you set the current limit, you get a constant current power supply. Set the limit by turning the voltage up a bit, shorting the leads and setting the current by the meter. You can now directly drive/test LEDs and other current devices without a dropping resistor. In this mode, the voltmeter will indicate the voltage on the device. For LEDs that would be the forward voltage. You can measure / test zener diodes the same way. Set the current limit to some value 5-20ma maybe, then connect the zener in the back-biased direction (cathode to +). The supply will limit the current to 5-20ma or whatever you set it to and the voltmeter will indicate the zener voltage at that current. Note that the voltage should be set to something reasonable. For LEDs, set it to less than the reverse voltage spec. For zeners, set it to something above the zener voltage or for an unknown zener, start low and increase the voltage until the supply goes into CC mode. That's the zener voltage at that current.

From a practical matter, you only use constant voltage OR constant current at one time. To use both would represent a constant power into the load. Not unheard of but not as common as using one or the other.

Have fun!

 

The constant current limiter function (as opposed to a foldback current limiter) does as it's name implies i.e. will limit the current drawn by your circuit to some constant value. If the load tries to draw more than that current, the voltage will drop.

Two things I use CC limit are:

Setting it to some value a bit above the maximum expected for the circuit under test. That way inadvertent short circuits will be limited to that value protecting the circuit, probes, electrolytics, etc. If a capacitor is in backwards, the CC light turns on. That's better than the cap exploding

Also useful when you set the current limit, you get a constant current power supply. Set the limit by turning the voltage up a bit, shorting the leads and setting the current by the meter. You can now directly drive/test LEDs and other current devices without a dropping resistor. In this mode, the voltmeter will indicate the voltage on the device. For LEDs that would be the forward voltage. You can measure / test zener diodes the same way. Set the current limit to some value 5-20ma maybe, then connect the zener in the back-biased direction (cathode to +). The supply will limit the current to 5-20ma or whatever you set it to and the voltmeter will indicate the zener voltage at that current. Note that the voltage should be set to something reasonable. For LEDs, set it to less than the reverse voltage spec. For zeners, set it to something above the zener voltage or for an unknown zener, start low and increase the voltage until the supply goes into CC mode. That's the zener voltage at that current.

From a practical matter, you only use constant voltage OR constant current at one time. To use both would represent a constant power into the load. Not unheard of but not as common as using one or the other.

Have fun!

Thanks. I intend to.

That does confirm my interpretation of how the CC is supposed to work ie: maintain the current by varying the voltage.
No other way of doing it really.

The great news is I just did what you suggested ie:

Set the limit by turning the voltage up a bit, shorting the leads and setting the current by the meter.

.... and it works. It's now in CC mode. Brilliant. Made my day.

Is this a standard feature of this kind of device or do you have this particular unit yourself?

How do I put it back in CV mode? Is there a procedure for that?

Thanks again

 

How do I put it back in CV mode? Is there a procedure for that?

Just increase the current limit value (set the switch to A and use the knob) to something more than what the circuit requires. Then it will be in CV mode. It's automatic. If you're pulling less than the current limit, it's CV. If you pull more, it limits the current and you're in 'constant current' mode. Note that constant current does not mean that the power supply always pushes that much current to the load. When the load is small enough so that it does not pull the current set by the CC control, the voltage is limited by the CV setting, the current will drop and you'll be in CV mode automatically. CC usually means a load impedance low enough that it won't have a significant voltage across it at its rated current. Think those diodes, or the shorted leads.

 

Just increase the current limit value (set the switch to A and use the knob) to something more than what the circuit requires. Then it will be in CV mode. It's automatic. If you're pulling less than the current limit, it's CV. If you pull more, it limits the current and you're in 'constant current' mode. Note that constant current does not mean that the power supply always pushes that much current to the load. When the load is small enough so that it does not pull the current set by the CC control, the voltage is limited by the CV setting, the current will drop and you'll be in CV mode automatically. CC usually means a load impedance low enough that it won't have a significant voltage across it at its rated current. Think those diodes, or the shorted leads.

Just done that. Sorted. Thanks again. Really. Exactly what I needed to know. Much appreciated.

I have a lot to figure out so I am probably going to be hitting the forum a lot.

 

To set Current, push select switch to A, and set output with rotary potentiometer, connect load and it will give the Constant Current, the voltage will vary according to the resistance of the load to maintain the desired current.

Thanks Dodgy. I missed your comment. Not getting noifications for some reason.

 

A general note power supplies are effectively:

CV and overcurrent protection (e.g. fuse)
CV and current limit (this does not provide precise regulation)
CV and foldback current limiting. I have a 10A supply with this that you can short and the voltage drops to nearly zero
CV CC The mode changes.

With some supplies, you can't set the value of current without being in current regulation e.g. a load or shorted leads.
In general, you use it to protect what your working on.

CC would be used for LED's, for instance.

You can look at supply in CC mode where the Voltage setpoint is the maximum compliance. e.g. set to 100 mA or 10 V. When the leads are open you won't see more than 10V on the output.

This http://literature.cdn.keysight.com/litweb/pdf/5952-4020.pdf should be a good read.

 

A general note power supplies are effectively:

CV and overcurrent protection (e.g. fuse)
CV and current limit (this does not provide precise regulation)
CV and foldback current limiting. I have a 10A supply with this that you can short and the voltage drops to nearly zero
CV CC The mode changes.

With some supplies, you can't set the value of current without being in current regulation e.g. a load or shorted leads.
In general, you use it to protect what your working on.

CC would be used for LED's, for instance.

You can look at supply in CC mode where the Voltage setpoint is the maximum compliance. e.g. set to 100 mA or 10 V. When the leads are open you won't see more than 10V on the output.

This http://literature.cdn.keysight.com/litweb/pdf/5952-4020.pdf should be a good read.

Cheers.

 

A general note power supplies are effectively:

CV and overcurrent protection (e.g. fuse)
CV and current limit (this does not provide precise regulation)
CV and foldback current limiting. I have a 10A supply with this that you can short and the voltage drops to nearly zero
CV CC The mode changes.

With some supplies, you can't set the value of current without being in current regulation e.g. a load or shorted leads.
In general, you use it to protect what your working on.

CC would be used for LED's, for instance.

You can look at supply in CC mode where the Voltage setpoint is the maximum compliance. e.g. set to 100 mA or 10 V. When the leads are open you won't see more than 10V on the output.

This http://literature.cdn.keysight.com/litweb/pdf/5952-4020.pdf should be a good read.

That's a great PDF. Just had a scan through it. I want to do a lot of projects using transistors so this should help a lot.