[modeleng] Re: Topsy - to charge and how to charge, that is the question! - modeleng

[modeleng] Re: Topsy - to charge and how to charge, that is the question!

From: "R.L. Roebuck" <rlr20@xxxxxxxxxxxxx>
To: "'modeleng@xxxxxxxxxxxxx'" <modeleng@xxxxxxxxxxxxx>
Date: Wed, 30 Mar 2005 14:17:57 +0100 (BST)

On the face of it, that sounds good to me - you are kind of using the
driver as the control system - but this will probably increase the fun of
running the loco - and heck, we do it with the steam loco's.

Would still have a play with the arrangement on the bench if there is even
the slightest chance that you may be wasting effort by setting the whole
thing up in the loco.

One slight thing to watch for, I think there is some issue with
disconnecting the battery from the alternator whilst the engine/alternator
set is running - possibly could cause damage to its voltage regulator (as
you switch from batterys to dummy load there will be an instantanous
change in current, this will cause a voltage spike due to the inductance
of your wiring and the alternator - this spike could easily kill anything
silicon based, such as the voltage regulator - your speed controller
should be safe, as you will have switched this out of the circuit).

Switching off the excitation current into the alternator (with a freewheel
diode on the alternator side of the switch) is a safe way of reducing the
alternator output current to zero, whilst you change from battery to dummy
load or visa versa, before you switch the excitation current back on again
- but this is again getting more complex. There may be a simpler way
around this though, or something I'm missing.

Yours,

Rich.

On Wed, 30 Mar 2005, Peter Sheppard wrote:

> Firstly, apologies for the big snips - the mailing list only allows 20 lines 
> of
> text carried forward!
>
> OK, I was trying to make this a KISS project (keep it sweet and simple!)
>
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[modeleng] Re: Topsy - to charge and how to charge, that is the question!

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