(3) Q4 and Q5 are arranged with transformer T2 in a free running oscillator at
approximately 2.5kHz, and runs as long as the main power is turned on.
(4) The secondary, or isolated side, delivers a regulated 12v, designated as
floating 12v, to all high voltage support circuitry as well as to the delivered energy circuits
(described later). These voltages are isolated and referred to the negative side of the high
voltage as opposed to circuit ground.
e. Functions of the Circuits in the Power Invertor and High Voltage Supply.
(1) The main power invertor consisting of T7, Q1, Q2, U1, U2, and U3 is so
arranged that it will oscillate (produce high voltage on the secondary side) as long as there
is no ready signal. A ready signal only comes on when high voltage is delivered in
sufficient amount to match the selected energy chosen by the operator and as long as
(2) This second requirement is taken care of by a section of SW5 and
arranged so that when internal paddles (low energy only) are used, the machine cannot
charge beyond a selection of 50j.
(3) The oscillator develops two out-of-phase signals of approximately 40kHz.
They are optimized in terms of waveform and duty cycle by U2 and buffered by U3 and
become the drive signals for the 2 power MOSFET invertor transistors Q1 and Q2, which
are mounted directly on a heat sink.
(4) The high voltage outputs from transformer T7 are subsequently applied to
rectifiers CR10 through CR17 which are configured as voltage doublers. Each has a high
voltage capacitor C10 and C11 in their common legs.
(5) These capacitors prevent the capacitors in the storage bank C12 through
C19 from attempting to charge up instantaneously, thereby controlling the overall charge
time. CR46 through 49 are connected across each portion of the capacitor bank to limit
reverse voltage across the capacitors to a safe valve in the event of unequal discharge
(6) There is a string of zener diodes, a current limiting resistor, and the LED
portion of an opto-coupler U6 through U9 across each quarter of the capacitor bank. They
are all equal and intended to produce an output to the phototransistor at approximately
(7) All four opto-couplers have their outputs in parallel. Whichever opto-
coupler is turned on first produces an output called ready voltage.