diy-EGOR

[rr]

Before hooking up that expensive NTK to your newly built circuit,
it is nice to be able to test it out. I have a heater circuit built and
did the setup and test this way.

Use a 3.3 ohm (or there-abouts) resistor of 5 to10 watts in place
of the NTK heater. Setup a current meter in series with this resistor.

Power up the circuit and set pot R19 (or R15?) for a current
of 1.2 A. (this is the 'current limit' pot).

Change 3.3 ohm to a 10 ohm resistor (or add in a 5.6 ohm). Setup
a volt meter to read the voltage across the 10 ohm resistor. Adjust
R20 to give 10.0V across the 10 ohm load resistor.

The Vss_volt_adj (Q7-C) should be low (< 0.6v) with the 10 ohm
resistor. And should be > 5v? with the 3.3 ohm resistor load.

If you have a regular 'ole heated O2 sensor around, it can be used
to do a final test of the circuit. Hook up the heater only and power
up the system. By monitoring the heater volts & amps, along with
the Vss_volt_adj, make sure that the heater current never goes
above 1.2A, and the heater voltage nevers goes above 10.0v.

As the heater heats up, the voltage will increase until it reaches
10.0v, then current will drop maintaining the max of 10v. At the
10v trip point, the Vss_volt_adj will also go low.

Once I have the Ip circuit built, I'll see what can be done for setup
and test there. This one looks to be a mite more difficult.

hth's,

BobR.


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