Homemade NiMH Charger working not correctly

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DanielEurope

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Last week I assembled NiMh charger by below mentioned diagram. Charger working good, except LED indicator - it should light during charging, but nothing happened. I measured voltage on this LED, it is only 0.7 V........So I replaced resistor with lower resistance, but no success Is there anyone who can help me to figure out, why Led isn't lighting during charging, please? Thanks, Daniel

www.circuitdiagram.org/automatic-nimh-battery-charger-circuit.html
 
At a first look at that circuit, be happy that it is charging the batteries.

As for the LED, the design of that circuit as a charge indicator is ay best marginal and very dependant on component and battery characteristics.
In my opinion, it is not worth worrying about.

JimB
 
The LED indicator part of the circuit as shown won't work. If you want a LED indication of when the battery voltage reaches a target value then a voltage comparator should be used, with a switchable threshold voltage according to how many cells are in the battery. But as Jim says, it's probably not worth it.
 
Diode 1
N
 
  • Diode 1N4001 was connected backwards anode should be connected to ground of 5V Reg then cathode to + side battery so diode is in fwd bias .
 
Legardo said:
Diode 1N4001 was connected backwards anode should be connected to ground of 5V Reg then cathode to + side battery so diode is in fwd bias .
Click to expand...
Diode is connected correctly.
Lm7805 is being use as a current regulator, not a voltage regulator.
 
This is a two year old thread, revitalised by someone providing incorrect information.

Thread closed.

JimB
 
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