Current mirror for parallel led current matching

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treez

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In figure 3 of the following, the LHS transistor has its Base and Collector shorted.

**broken link removed**

....the LHS led string also has less current in it, due to the vf's of its leds being higher.

What if the base and collector of the RHS transistor had been shorted instead...would the current mirror still have worked?
 

The base-emitter voltage is a range of voltages so the actual amount of current in the current sink is a wide range.
The transistors probably do not match (but it is better since they are thermally joined) so the currents probably will not match as well as the example.

The base currents are on the left side so I think the LED current is higher in the left side.
 
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treez said:
What if the base and collector of the RHS transistor had been shorted instead...would the current mirror still have worked?
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I dont see why not

I also agree with audioguru that currents on the LHS should be higher
 
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It is the power supply that is limiting the currents, not the current mirror that on the left is simply some LEDs in series with a diode.
Since there are two LED strings then the 700mA from the power supply is simply divided roughly in half.
 
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