Re: Motor Control Circuit Problem

From: Helmut Sennewald (helmutsennewald_at_t-online.de)
Date: 10/29/04 

Date: Fri, 29 Oct 2004 20:57:02 +0200

"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> schrieb im Newsbeitrag
news:ntg4o09l7ko7a0vargfrilao9ej35n8hb1@4ax.com...
> Out of interest I tried simulating the original (symmetrical) circuit
> http://www.electronic-circuits-diagrams.com/motorimages/3.gif
> with CircuitMaker. But after an hour or so I'm darned if I can get it
> working. Typical error messages include:
> Warning: Gmin step failed
> Warning: source stepping failed
> doAnalyses: Iteration limit reached'
>
> Anyone care to try it in some other package please, such as LT
> SWCADIII? I'm assuming there's some nifty trick for getting an
> H-Bridge to converge in Spice...

Hello Terry,
you don't need another simulator, instead you need a correct
circuit diagram. Your circuit will never work as intended.

Let's look for example to Q4 and Q3 where the (base-)current flows.
It flows from
+9V -> Emitter Q4 -> Base Q3 -> Emitter Q3
regardless you drive any base current by Q1.
This is a short from +9V to ground by 2 Vbe-diodes.

>From where do you have this wrong circuit diagram?

Best Regards,
Helmut