Hi , i have a power dc-dc converter that is CV and CC adjustable through two different trimmers. It's characteristics are being attached in the picture below. The CC mode is adjusted through a 5k trimmer. I would like to ask the following: if I replace it's 5k trimmer with a 7k or 10k one , would the CC mode be able to apply a further decrease in the output current? It's specific characteristics refers that it allows a decrease onlu up to 200mA output current. I would like to modify it , to allow a decrease up to 20 mA output current. Is it possible? Thank you!

 

if I replace it's 5k trimmer with a 7k or 10k one

No that will not work.
Do you have a schematic? No ... these Chinese boards to not come with one. What is the IC? Some times they remove the numbers from the parts just to make life hard.

 

that looks an interesting board,
do you have a link to it please

 

Why do you want 20mA constant current source? Tell us what it is that you want to power.

Note that CV and CC settings are maximum limits. You cannot have both at the same time. The power supply will reach one of the two limits which ever comes first.

 

Only way to know is to look up the chip number and get it's datasheet.

For 20mA limit a LM317 will do.

 

No that will not work.
Do you have a schematic? No ... these Chinese boards to not come with one. What is the IC? Some times they remove the numbers from the parts just to make life hard.

 

Only way to know is to look up the chip number and get it's datasheet.

For 20mA limit a LM317 will do.

 

that looks an interesting board,
do you have a link to it please

https://www.banggood.com/Geekcreit-...8834201711&custlixnkid=64999&cur_warehouse=CN

 

Why do you want 20mA constant current source? Tell us what it is that you want to power.

Note that CV and CC settings are maximum limits. You cannot have both at the same time. The power supply will reach one of the two limits which ever comes first.

I have made a device that needs to have a Voltage output of 60 V and an output Current that does not exceed 20mA.

 

View attachment 216318

Yes it can be modified for lower current or voltage, the reference pins are 1,2 and 15,16, which pin is the current preset on ?

 

Yes it can be modified for lower current or voltage, the reference pins are 1,2 and 15,16, which pin is the current preset on ?

Will you understand if I send you again a picture that shows an overal top view of the board? Sorry , but i just know basic electronics and I need to make this modification.

 

If you need just 20ma out then this board is not the one I would pick.
It is way over powered for the job so you may well have trouble getting it to run at such a low setting. there is usually a minimum current required for them to work at.
You have chosen a "400W" power supply to run at a bit over 1 watt. Not the best thing to do. For a start, look for a lower power version.
What is your input power supply?
you say, "I have made a device that needs to have a Voltage output of 60 V and an output Current that does not exceed 20mA."
And, it usually helps if you tell us what you are trying to do in detail, not hiding things. Do you meen this device required 60V input from the power supply, or the device outputs 60V?

This may help...
https://www.ti.com/lit/ds/symlink/tl783.pdf

 

I think there is a 0.01 ohm resister. Change this to 0.1 ohm and you will get 20mA to 1.2A.

 

I think there is a 0.01 ohm resister. Change this to 0.1 ohm and you will get 20mA to 1.2A.

That is well worth a try!

 

If you need just 20ma out then this board is not the one I would pick.
It is way over powered for the job so you may well have trouble getting it to run at such a low setting. there is usually a minimum current required for them to work at.
You have chosen a "400W" power supply to run at a bit over 1 watt. Not the best thing to do. For a start, look for a lower power version.
What is your input power supply?
you say, "I have made a device that needs to have a Voltage output of 60 V and an output Current that does not exceed 20mA."
And, it usually helps if you tell us what you are trying to do in detail, not hiding things. Do you meen this device required 60V input from the power supply, or the device outputs 60V?

This may help...
https://www.ti.com/lit/ds/symlink/tl783.pdf

This device requires to output 60V and i do it through this dc-dc power converter. The power source of this device is two 9Volt batteries in series.

 

View attachment 216327
I think there is a 0.01 ohm resister. Change this to 0.1 ohm and you will get 20mA to 1.2A.

Ok , so you mean that if i replace that SMD to a 0.1 Ohm one , the output current will get from 20mA lowest to 1.2 A maximum? Moreover , because i haven't used SMD before , do we know what type this SMD can be , in aspect of it's dimensions? Thank you very much!

 

If the 20mA set limit is critical and an upper adjustment limit of 120mA is acceptable, I'd even be tempted to swap the 0.01Ω resistor for a 1Ω one, to make adjustment a bit easier and avoid having the required set point right at the end of the trimmer track.

 

If the 20mA set limit is critical and an upper adjustment limit of 120mA is acceptable, I'd even be tempted to swap the 0.01Ω resistor for a 1Ω one, to make adjustment a bit easier and avoid having the required set point right at the end of the trimmer track.

Thank you very much for your answer! The fact is that I haven't used SMD before , so do we know what type this SMD can be , in aspect of it's dimensions? Thank you very much!

 

do we know what type this SMD can be , in aspect of it's dimensions?

Get one the same dimensions as the 0.01Ω for an easy fit. It only needs a very low Wattage rating.

 

Get one the same dimensions as the 0.01Ω for an easy fit. It only needs a very low Wattage rating.

Why do I need low Wattage rating and approximately where the Watts should be? Thank you!