Samlex America SAM-1500C-12 - Manual (Page 8)

6 | SAMLEX AMERICA INC.
SECTION 2 | Features, Applications &
Principle of Operation
!
caution!
Certain devices (few examples given below) may malfunction when powered from Modi-
fied Sine Wave. Check with the manufacturer of the device for suitability of powering
with Modified Sine Wave:
• Devices utilizing zero voltage crossing for timing control: Some clocks used in consumer
electronic items (will not keep accurate time)
• Devices using modulation of RF signals on AC lines during zero crossing e.g. X-10 System
for Home Automation
• Devices utilizing Triac based phase control for transformer less voltage step down e.g.:
• Small battery chargers for hand tools, flashlights, night-lights, shavers etc.
• Variable motor speed control in hand tools
• Light dimmers
• Temperature controllers e.g.:
• Temperature Controlled Electric Blankets
• Devices using high capacitance based voltage multipliers for generating high voltage
(will create very high surge currents) e.g.:
• Photographic Strobe Lights
• Laser Printers
meaSurinG moDifieD Sine-WaVe VoLtaGe WitH
a “true rmS” VoLtmeter
As mentioned above, Modified Sine Wave voltage is a type of square wave that has an
RMS (Root Mean Square) value of 115 VAC. A general-purpose AC voltmeter is calibrated
to accurately measure the RMS value of a Pure Sine Wave and NOT of a Modified Sine
Wave. If this general-purpose voltmeter is used to measure Modified Sine wave voltage, it
will indicate a lower value (96 VAC to 104 VAC). for accurately measuring the voltage of a
Modified Sine Wave, use a voltmeter which is designed to measure “True RMS Values” like
fluke 87, fluke 8060A, fluke 77 / 99, beckman 4410 etc.
principLe of operation anD cHarGinG aLGoritHm - Battery cHarGer
The battery charger is a 2 Stage, Switched Mode Design using fly back Topology.
120 VAC from the AC Input is rectified to high voltage DC of around 170 VDC, which is
then converted to high frequency pulses using MOSFET Switch and then stepped down
through switching transformer. The transformed voltage is rectified and filtered. A sample
of the output voltage is used as feedback signal for the drive circuit for the switching
Mosfet to achieve desired voltage regulation of 13.8 VDC using Pulse Width Modulation
(PWM). It is designed to provide maximum charging current of 15A.