Recent content by lkari

hi guys, i understood everything of what you r saying proton soup. I am an electrical engineer. With background in mixed signal circuit design as well as IC Packaging. I am just having problems reading out datasheets and choosing rt components. yea I replaced the 2N3906 with BC328-40...

I had one question, the opamp stage is totally not the load carrying stage and so only needs to operate at the supply voltage and nothing else rt? and also if the negative terminal of the opamp maintains the supply voltage, then how would there be a current in the emitter resistance? that too...

yea makes sense to me now. I will try simulating the circuit and write back what happens so other may benefit. Also by tweaking the resistance between the diode anode and the input positive to the opamp, we will be able to get the input close to teh supply. i could get it as close as around 95%

but then in using a pass transistor of vbe approximately 0.9 volts, the base and the emitter will be almost at the same voltage and not operate teh transistor in the required region of operation rt? it need to be in the active region. so the vbe should be slightly less than -2 V for all ranges...

hmmm yea. but what would limit the open loop gain here? then what criteria determines the input to th eopamp? is that what we want as the emitter voltage for the pass transistor?

should the opamp input operate very close to the supply? I thought the bottom resistor was to maintain teh minimum current through the zener. then the other two resistors i thought are as voltage divider. please correct me if i am wrong

but what abt the alpha paramenter? that changes with the transistor currents rt? which is teh load current? so not just the value of thr emiter resistance but the alpha value is also varying while we try to vary the load current. rather is it that the alpha value is stablized by the opamp...

that was how the circuit was described. it means the transistor parameters change teh load current rt? would that be a bad design?

Hi Please c the following circuit. how can I decide the specifications of the opamp? I will be choosing a BC 328-40 pnp transistor for the output stage. It will be bale to take a maximum collector current of 800mA, a little more than my requirement. the input to the opamp is through a...

So let me start from the begining. I am using an OPA 547 high precesion high current opamp to build a power supply. I used the application note for the opamp 547 in its datasheet. SO now the problem is that I am not able to control the output current. I am using TINA Ti simulator for simulating...

Hi the maximum rating on the opamp is 500 mA and I am not exceeding it. I am worried that I am not able to work properly with the inputs and supplie sto the opamp. I am using an OPA547 . I am reffereing to teh datasheet and there is also a application note on current source design. I am not...

i really don't understand why they are on the same subject. one is about the circuit the other is about reading the data sheet for the component. << post edited by berkeman to clean up txt speak >>

So the output of the opamp should be independent of the load you mean right? please correct me if i am wrong. Thanks in advance Kari << txt speak edited out by berkeman >>

Current amplifier Hi I am trying to build an adjustable current supply using an opa547, so the thing is the output current is dependent on the load that i am attaching. I was wondering as to what I could do to get rid of this dependence? Thanks in Advance Kari

I reffered to it but, what do they mean by saying the following there? (V+) –3