Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Will this current sink work?

Status
Not open for further replies.

UroBoros

Advanced Member level 2
Advanced Member level 2
Joined
May 5, 2004
Messages
642
Helped
19
Reputation
38
Reaction score
8
Trophy points
1,298
Location
Cochin - India
Activity points
6,463
fast current sink

I need a variable load which can sink 0 to 500mA at 60volts. Need to vary current sink using a potentiometer.

Please see weather this circuit will work as simulated. As I am new to simulation I have some doubts regarding the way I configured the power rails in Proteus. So I doubt about the result of simulation.

Thanks
 

To make it working, V(+) ==V(-) [opamp inputs] ..
For max current 0.5a the voltage across R3 ≈ 2.5V, so the voltage divider R4/RV1 has to produce similar voltage, that is max. 2.5V ..
Also, Q1 has to have a decent heatsink (60V * 0.5A) ..

Rgds,
IanP
:D
 

    UroBoros

    Points: 2
    Helpful Answer Positive Rating
Thanks a lot. meeting :D after a long gap :cry:

But R3 is only 0.5 Ohms(Not 5 Ohms). So 0.3Volts only on pin no 3 of Opamp.


Is it Ok then?

Thanks
 

No. The circuit can only work with an OP, that has a common mode range including negative supply. This isn't the case with TL081. Additionally, as the OP is driving a large capacitive load, it may require a small compensation cap from output to negative input in some cases (particularly a fast OP).
 

    UroBoros

    Points: 2
    Helpful Answer Positive Rating
I suggested using a different OP, but dual supply can work as well. A compensation cap should be used if oscillations occur.
 

    UroBoros

    Points: 2
    Helpful Answer Positive Rating
FvM said:
I suggested using a different OP, but dual supply can work as well. A compensation cap should be used if oscillations occur.

I have changed the OP to OP07 and introduced dual supply.
Can you suggest a common OP which can be used for this purpose with single supply?

Thanks
 

Picstudent said:
Can you suggest a common OP which can be used for this purpose with single supply?
Thanks
TLC2272 / TLC272 / LM358 / LM324 can be used.
 

    UroBoros

    Points: 2
    Helpful Answer Positive Rating
Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top