DIY_UEGO

[rr]

This is good news. It will help in reducing the cost. The n-chn (IRF150/IRFZ24)
can probably be changed to a 2N7000. 43 cents in digi-key: 2N7000-ND. This
is a TO-92 cased mosfet, 10v gate, 5 ohm on resistance.

The p-chn in the heater circuit can be changed to any number of devices:

    IRF9Z20
    IRF9Z24
    IRF9Z24N

These are all about $1.50. I choose devices with a low on resistance as this
will still allow the circuit to run at lower voltages. Still need to heat sink them.

Looking at the batteries in the circuit and it doesn't make sense. I don't see
a need for any. My guess is that these are the pump cells and the diodes
(D7 & D8) are really part of the sensor. Also remember that the schematics
were done in PSPICE, looks like to be modeled. If this is true, then R5
is also part of the sensor. Anyone?

BobR.

Chad Clendening wrote:

> THe N channel fet can be any n channel mosfet, just don't use a logic level with that
> circuit.
> The P Channel should also be pretty universal but this needs to get rid of 5 watts of
> power sometimes.
>
> The FETS just happen to be on my shelf during proto work.
>
> The 2N3904 is a NPN transistor
> 2N3906 is PNP and both are very common.
>
> Chad
>
> ----------------------------------------------------------------------------
>

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