Hi from Alaska,

As winter is settling in, I am catching up on a few electronic projects on my list and one of them is a smart charger for my RV dc system.

I found a simple circuit on the Internet that provides the adjustment of turning on and off the charging output by setting the max and min voltages for operation.

However, the circuit provided uses abbreviations for component values that I believe are common in some foreign country. For example, there are two variable resistors (with slider taps) with these notations on the circuit:
VR1 500V (no ohms indicated or value like a "k")
VR2 1 K this seems to be a typical 1 K ohm variable resistor

There are three more resistors in the circuit:
R1 3.9 K aslo seems to be a typical fixed 3.9K resistor
R2 290 V another big question mark for me
R3 15 V and another unknown

Is the "V" another code for "ohms" ? Are they typos ?

This circuit uses a single power transistor 2SC1061, a 12 VDC relay, a 1N4001 diode and the resistor network make up a comparative window to turn the transistor on or off which energizes or de-energizes the relay to switch on or off the charging current.



Can anyone clarify for me the values of these five resistors for me?

Thanks in advance, Bill

 

No, 'v' is not another code for ohms, but apparently is used here as a
substitute. 'mf' should be 'uf', also.
Look here for more elaborate chargers:
Power Supply Schematics - page 5
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