From: RODERICK MAXWELL[SMTP:tank-at-mail.magnolia-dot-net]
Reply To: tank-at-mail.magnolia-dot-net
Sent: Wednesday, January 07, 1998 9:31 PM
Subject: Flyback Converter
The transistors came in Monday! I now have six IRF440 power mosfets
in parallel.They are all mounted on a large common heatsink. I am making
the sink do double duty because the transistors are not isolated from
the sink by mica insulators(case is drain). This enables me to use the
sink as a buss for all the transistor drains. This also gives better
heat transfer between the transistor case and the heatsink. The sink is
mounted on a piece of acrylic plastic to afford isolation from ground
and the rest of the circuit. Also mounted directly in front of the sink,
but not touching it is a 212cfm AC muffin fan for additional cooling.
On each gate there will be a 12ohm carbon composition resistor to
dampen inductive ringing in the gates. Also each gate lead will be
threaded through a ferrite bead to prevent self-induced ocillations.
Gate leads will be kept short, and of the same length to each gate to
ensure that all of the transistors turn on at the same time. The
connection to the primary of the transformer will be through the
Can anyone tell me how to calculate efficiency of a flyback converter?
I would like to know how much power is coming out of the other end!