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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Charger for finger batteries. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Chargers, batteries, galvanic cells

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Battery charger

UF1-Ube

R1=--------, where UF1 is the glow voltage VD1=1,8V (yellow), Ube is the base-emitter voltage KT815A = 0,7V

I2

Up-Ua-UF2

R2 = ----------, where Up - power supply = + 5V, Ua - voltage of a charged battery = 1,45V

I1

UF2 - glow voltage VD2 \u1,5d 1V (red). where I1 is the charge current (approx. 100/XNUMX of the main charge current)

I2 - main charge current - recharge current (approx. 1/10 of the main battery capacity)

Example: for a 1000mA battery, charge current = 100mA base current = 90mA + recharge current = 10mA.

I1=~10mA, I2=~90mA,отсюда R1=1,8-0,7/0,09 = ~12,2 Ома. R2=5-1,45-1,5/0.01=~205 Ом.

Using a 4-channel op-amp, you can assemble a charger for 4 batteries. Any op-amp powered by 5 volts.

See other articles Section Chargers, batteries, galvanic cells.

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