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From: "Frank Bemelman"
References: <3D80CE15.7AA8F912@xympatico.ca> <email@example.com>
Subject: Re: Engineering Assistance Needed
Date: Fri, 13 Sep 2002 17:12:47 +0200
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
Organization: EuroNet Internet
NNTP-Posting-Date: 13 Sep 2002 15:13:16 GMT
"Ed Edmondson" schreef in bericht
> Still no luck...... I swapped pins 2 and 3 on the comparator. I wired the
> amp output through a 1,000 ohm resistor to the gate. I added a 10,000 ohm
> resistor from plus 5 volts to the gate. I wired the source to ground and
> drain through an LED and limiting resistor to plus 5 volts to test the
> configuration. With 1.697 volts at the wiper of the pot I have 4.06 volts
> the gate and the LED is on. With 4.88 volts at the wiper of the pot I have
> 2.692 volts on the gate and the LED glows slightly. With 2.689 volts on
> wiper of the pot I have 4.02 volts on the gate and the LED comes on to
> brightness. With this configuration the LED or relay won't turn off. The
> is a NAIS model TQ2-4.5v DPDT with a coil resistance of 150 ohms. Since
> didn't turn completely off I didn't try the actual load.
Can you measure the voltages on the opamps' output, and also at the gate?
Check with a meter if your resistors have the right value - it's easy
to mistake red for orange...
> I have double checked the wiring on the plug board and there are no wiring
> errors. I have change the 530 to insure it wasn't the FET. I tried another
> manufacturer of FET and nothing changes.
> Why is something so simple unable to work?
A lot of things start of as 'not working'. Even the simplest stuff.
In the end, it is often a very silly error, but you have to find
it first. No panic ;)
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