Hi,
I bought a new power supply for 18 bucks. On the daughterboard on top there are 2 leds which say CC and CV. I think it means constant current and constant voltage. The default setting is constant voltage but I want to have a constant current and I can't seem to find a way to do that. I tried the manual and sites but no luck on this. The power supply is a MingHe d3806

 

If there is no load then there can be no current so the output voltage will rise up to the voltage limit.
With a short circuit on the output there will be no voltage so the output current will rise up to the current limit.
With a 10Ω load on the output, the current limit set to 1A, and the voltage set to 9V the output voltage will be 9V and the current will be 0.9A (constant voltage mode). If the voltage is turned up to 11V the output will be 10V, the current will be 1A (constant current mode).

So which mode it is in depends on the setting of the controls and the load.

If you have a load which requires constant current, set the voltage to maximum and the current as desired.

 

If there is no load then there can be no current so the output voltage will rise up to the voltage limit.
With a short circuit on the output there will be no voltage so the output current will rise up to the current limit.
With a 10Ω load on the output, the current limit set to 1A, and the voltage set to 9V the output voltage will be 9V and the current will be 0.9A (constant voltage mode). If the voltage is turned up to 11V the output will be 10V, the current will be 1A (constant current mode).

So which mode it is in depends on the setting of the controls and the load.

If you have a load which requires constant current, set the voltage to maximum and the current as desired.

At Max voltage the PSU starts making a hissing sound and it still gives only a constant current. My question was that if there is any way to set it from the settings of this unit.

 

My question was that if there is any way to set it from the settings of this unit.

NO.
As explained which mode it is in depends solely on the voltage and current settings and the resistance of the load.
This applies to all power supplies not just this one.

 

NO.
As explained which mode it is in depends solely on the voltage and current settings and the resistance of the load.
This applies to all power supplies not just this one.

Ok. How would you get a constant current for a changing resistance then? The load can take any voltage or current

 

Hi,
I bought a new power supply for 18 bucks. On the daughterboard on top there are 2 leds which say CC and CV. I think it means constant current and constant voltage. The default setting is constant voltage but I want to have a constant current and I can't seem to find a way to do that. I tried the manual and sites but no luck on this. The power supply is a MingHe d3806

Curious about of how you determined the "default setting". Wouldn't you be able to set the other option then?

 

Set the voltage to maximum and set the desired current.
As long as the set current flowing in whatever the load is produces less than the maximum voltage setting you will get your constant current.
If the load resistance is big enough that the maximum voltage is not sufficient to drive the set current through the load then the current will reduce but in this case you cannot achieve that current in that load with this power supply.

 

What is the maximum current rating of the power supply ? What output voltage have you set it to with no load and what value of load resistor are you using to get it into current limiting mode ? Posting some information on the power supply would have been be useful. For the sake of others trying to help you here is a link to some documentation on the device. After a very quick scan through the documentation it looks like the next step after setting the output voltage is setting the current limit. As Albert has already said you do not have to change from constant voltage to constant current mode. The current limiting comes in when the value of the current taken by the load exceeds the set value of current limit.

Les.

 

Curious about of how you determined the "default setting". Wouldn't you be able to set the other option then?

There is no default setting for this and no option to change it. It is determined entirely by the voltage and current settings and the load resistance.

 

Curious about of how you determined the "default setting". Wouldn't you be able to set the other option then?

That is what I thought but it seems like I was wrong

 

What is the maximum current rating of the power supply ? What output voltage have you set it to with no load and what value of load resistor are you using to get it into current limiting mode ? Posting some information on the power supply would have been be useful. For the sake of others trying to help you here is a link to some documentation on the device. After a very quick scan through the documentation it looks like the next step after setting the output voltage is setting the current limit. As Albert has already said you do not have to change from constant voltage to constant current mode. The current limiting comes in when the value of the current taken by the load exceeds the set value of current limit.

Les.

Ok so I tried what you said and now it works. Thanks a lot for your help! Since the resistance of the load changes, I needed a changing variable (such as voltage) that I could measure(easily) on my oscilloscope and find the relation between the temperature and the resistance. Thank you les and Albert

 

It would help if you explained what you want the constant current power supply for.

Les.

 

It would help if you explained what you want the constant current power supply for.

Les.

Yeah sorry