[Diy_efi] schematic critique

[Bill Washington]

J,
    The following are basic circuit comments, I have not looked at it 
from a functional point of view.

1. Schematic 1 requires another protection diode on the relay drive 
(Anode to GND, Cathode to signal) to prevent the negative spike (when 
the relay is released from blowing the opamp.

2. Schematic 2 :
a. Comment 1 applies.
b. series resistor reqd between opamp and transistor base
c. Transistor collector should go to +ve supply, Emitter should go to 
the relay coil.

Regards
Bill

>
>Date: Sun, 16 Feb 2003 18:50:49 -0500
From: "Toyota Supra" <turbosupramk3 at hotmail.com>
>To: diy_efi at diy-efi.org
>Subject: [Diy_efi] need schematic critique
>Message-ID: <BAY2-F94ArbDVL7IZQI0002de3e at hotmail.com>
>Content-Type: text/plain; format=flowed
>MIME-Version: 1.0
>Precedence: list
>Reply-To: List for general do-it-yourself EFI talk <diy_efi at diy-efi.org>
>Message: 1
>
>hi all,
>
>i need a schematic critique on the schematic housed below, it is in .jpg 
>format or .psd
>
>http://68.7.7.84:8080/schematics/
>
>i have included the psd in case someone wanted to edit it to something 
>better
>
>specifics on it are as follows :
>
>variable resistor input, ranging from 0 to 3.5vDC
>circuit is to kill signal to normally open relay at 3.2vDC
>i would like approximately a tenth of a volt of hysteresis
>
>
>below is a link that i would like to use to control the reference voltage 
>for pin 4 of the LM339 chip, will it work?
>
>http://www.mitedu.freeserve.co.uk/Circuits/Power/lm317.htm
>
>
>thanks to all that look at this
>
>-j
>
>
>  
>



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