Plug Top PS charge indicator
From
G8MNY@4:902/6 to
WW on Wed Jan 8 08:00:44 2025
By G8MNY (New Jan 21)
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Here is a circuit used in a small kit battery charger. The battery kit has a battery disconnect feature when fully charged (thermal or voltage end point) etc. & reduces the plug top load.
+20V off load 16V charging
ÚÄÄÄÄÄÂÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ>+V
³ ³ 10V_³_
³ ³ '/_\
L<ÄÂÄÄÄthÄÄ¿ __/+\_ ³ ÚÄÄÄÄ´
m22 fuse )||( ~\-/~³ ³ ³ 470R
neon )||( ³ ³ ³ 15K ÃÄÄÄÄ¿
³ )||( ³ ³ ³ ³ 680R _³_ CHARGED
N<ÄÁÄÄÄÄÄÄÄÙ ÀÄÄ)ÄÄÙ ³ ³ ³ \_/ð RED
³ +³ ³ ÃÄÄÄÄ´
³ 1m=== ³ ³/ _³_ CHARGING
³ 25V³ ÃÄÄ´NPN \_/ð GREEN
³ ³ 1K ³\e ³
ÀÄÄÄÄÄÁÄÄÄÁÄÄÄÄÁÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄ>-ve
It relies on the voltage drop of the simple PSU on load to work the indicator electronics.
When load is off the voltage overcomes the zener drop & lights the LEDS. But also turns on the NPN, shorting out the green LED.
When load is on, the voltage still overcomes the zener drop & lights the LEDS. But not enough to turns on the NPN, & the green LED lights & on the lower voltage the 680R across the red LED stops it lighting.
If LEDs are not lit there is either no power or PSU is overloaded!
Adjustments for your PSU might be to make the 1K a 2K2 preset, & select the zenner voltage for your PSU, so that at least 6V is avalable to the cicuit when charging.
See my Tech Bul "Analyser SWIRES RESEARCH SA87"
Why don't U send an interesting bul?
73 de John, G8MNY @ GB7CIP
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