Modification of De-sulfator for 24 volt batteries
Note: Schematic below shows large battery option. Using 47K for R3 and a switch to shut
down oscillator during installation and removal from battery & charger.  If you fail to do so
with this modification, you will risk blowing out the transistor.
Circuit Operation
The pulser rides the 12-volt line on a trickle type battery charger and battery. The L2/C3input
filter isolates the pulse circuitry from the battery and charger. Stored Energy from C3 the 100uF
capacitor is switched into inductor L1. When the Transistor switches off, the inductor field
collapses and generates a burst ringing voltage on the order of 50–60 volts and   as high as 40
amps or more for about 20microseconds.This burst is repeated 1000 times per second. This very
high current is then dumped via the fast recovery diode back into the battery thrught the same
wires that power the De-sulfator.  High current pulses produce the secondary resonant ionization
of the sulfate precipitate electrochemistry and move it off the bottom of the cell and back to work
into the electrolyte solution.

Use a 2-amp fuse with the pulser. Do not hook  the pulser board up backwards!  Simply attach
the pulser unit to the output leads of a trickle battery charger and to your battery.  A highly
sulfated (non-shorted) battery may take as long as 2 weeks to recover to nearly new
performance. (For the more techie types--  Probing at the battery terminals with a differential
oscilloscope  will reveal a progressively declining burst amplitude as the battery recovers and its
internal impedance goes down.)

Regular use on your aircraft battery will restore the battery’s rated amp-hour performance life
and discharge capability.

Please note:  If you use the pulse de-sulfator on a battery installed in your aircraft do not turn on
the aircraft master switch while the de-sulfator is connected to the battery.  It is unlikely, but not
impossible that the high voltage pulse may get thru your avionics power input protection circuitry!
Be smart, be prudent. Take care of your radios!  

Use 560K (Green, Blue, Yellow) color code resistor for R2.  For R3 use 15K (Brown, Green,
Orange)  R1 is 300 ohms (Orange, Black, Brown) Note the polarity marks on the electrolytic
capacitors and orient properly. (C3 & C2 100uF and 10 uF negative lead is near white
Install  L1 & L2.  wires into the terminal holes and set the inductors in place as shown with hot
glue. Install the components in the circuit card as shown and solder use a short pieces of 16
gauge wires to connect the circuit board to the plus and minus leads of the battery charger.   The
box enclosure of the circuit card is left up to the imagination of the user.  You may mount it in the
battery charger case or in an external chassis box available at Radio Shack If any of you have 24
volt battery systems, increase the value of R1 to 620 ohms   and add a 12 Volt Zener diode  
(Radio Shack   PN  276-563 (1N4772A) $0.65  ) in parallel with C3 to limit the voltage on the
timer and inverter components.  
Dave Barker