I would like to use the LM334 with 9V batteries to produce an approximate 3mA constant current through a diode. But I am a little confused by the device schematic. This device has three leads (V+, ADJ, and V-) --- I have put a 25 ohm resistor between ADJ and V- to select the current I want. But I'm not sure where to put my diode? where does the constant current flow?
point (A) or point (B) whichever is most suitable. | (A) | |V+ ----- |LM |R |334|----. | | | --- 25R |V- | +------' | (B) |
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-- Into V+ or out of the junction of Rset and V-, so you can put your diode between the supply and V+ or between the junction of Rset and V- and ground.
A resistor and two-transistor current mirror will give you constant current in the 0.2 to 5V range of Shottky through LED diodes... use a 2.7k ohm resistor. Unless you need high accuracy, the IC is just an expensive bit of overkill.
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