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No, because the current through Rb will vary as the load resistance varies. It will be fairly high impedance, but you can improve it by moving RL to the collector of TR1.graemec said:
ok.
Is this a constant current source?
g
Hero, You concluded on the other thread that the supply voltage is too low. Graemec should have kept the discussion to that thread.Hero999 said:Yes, look on the datasheet for the LM317 which is easy to find from Google.
Do you still need up to 300mA, with a 5V supply?graemec said:Sorry so let me understand.
If I move Rl to the collector it will be constant current source?
Does anyone have any links to designs for constant current sources?
Thanks
Graeme
I tried to find a tutorial on the Internet, without much success. I have designed and built a LOT of current sources in my life, and I could describe some techniques, but I don't know what your level of understanding is.graemec said:Yeah I do.
But more importantly I want to improve my understanding. I've drawing a number of circuits which deliver a constant current irrespective of the input voltage but just realised that the current is highly dependent on the load which is really not what I want. I want a circuit that will deliver 300ma do any reasnoble load. If 300ma is not possible I want the most I can get.
Id like to be able to construct the circuit using off the shelf components rather than buy devices.
thanks for all the help so far.
G
OK, here's what is probably the most common voltage-controlled current source configuration, with several options for output current boosters (you can make low-current sources with just an op amp and some resistors).graemec said:I understand all these concepts.
any help would be great.
Graeme