Hi all
I have an old HP supply that is rated at 18.5V 6.5A DC. This is within the spec for a Lenz system. However, I recall from somewhere that the HP supply has some feature that would prevent this. Something to do with three wires on the output? The output pin shows P2 +, P1 D, P3 -.
So, can this supply be adapted to use with a DCC system?
bagal (currently happily locked down in our bubble)
Do you happen to have a model number? Yoiu cna probably find the pinout by googling.
The extra pin is for regulating the charge current, so usually you need to do some modification to make it output the full power on the main power pins.
HP it seems just uses a resistor, Dell and others actually send a serial datastream to the power supply.
There are always generic replacement laptop power supplies which aren't terribly expensive. Not the same as the free one you already have, but possible easier to use.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Thank you for replying Randy. It is 384023-003. There is a diagram on the back which shows P1 (D) at the centre, then P2 (+), then P3 (-) on the outer.
My current supply is only the 16V a.c. from an old controller which works fine as I only run one train at a time, but maybe more capacity would be useful.
bagal
Yeah the D pin is the thing, it's a control signal. I came across some links using Google that showed how to modify the HP/Compaq power supplies to output full current on the + and - lines at all times.
You definitely want a proper power supply. If the one you have doesn't supply enough current, it can make the command station do very strange things as the voltage sags - in that range between working fine and everything stops. Bad packets, a failing DCC signal - things can happen like locos taking off at full speed or the config getting scrambled.