[Diy_efi] DIY-WBO2 heater circuit

[bcroe at juno.com]

If you use switching to control heater current, you will have 
an electrical noise generator, a 10 watt transmitter.  That 
noise will try to get into everything nearby; the control 
circuit, audio amplifiers, and radio receivers.  

There are ways to filter such noise, but the filter will be more 
complex than the rest of the heater circuit.  This could be 
very educational, but perhaps not the simple answer you 
would like.

Bruce Roe


On Sat, 22 Jun 2002 16:55:53 +0200 =?US-ASCII?Q?Jorgen_Karlsson?=
<jorgen.m.karlsson at home.se> writes:
> Chad wrote:
> 
> > I PWM'ed a UEGO heater once, the thing started making noise.
> > Noise = vibration, I figured ceramic and vibration probably don't 
> mix.
> >
> > I didn't try adding an inductor in the circuit, that would keep
> > the current continuous.
> 
> That is useful information, I am trying to build a microprocessor 
> controlled UEGO controller and I had originally planned to
> PWM the heater directly.
> This is a resting project, one of the design criterias are 
> simplicity in circuit design and control logic. So far I haven't 
> been able to make a design that fulfill that, but I haven't put 
> much effort in it either.
> 
> Jorgen Karlsson
> Gothenburg, Sweden.

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