Hey gang,
Small progress!!! I just finished getting the air compressor to fire!!!!
As I said in an article in The Brickline, I was going to use a relay.
Someone on the list was saying that he did that, but he keeps burning
up the relay. Since my car isn't really in service, I can't give a true
report on how well this is going to work. I have made a small modification
from the original schematic that I drew for the article. I've placed some
"despiking" or "free-wheeling" diodes across the coil of the relay and the
compressor motor. I don't know if this is going to make much difference
either way though.
For the diodes, I used a diode of the 1N4001, 1N4002, 1N4003, ..., 1N4007
family, rated at 2.5A and 1KV. Shouldn't see any where near that amount
of back EMF. I also just thought that we should probably put a diode
in the control wire line, so we don't back feed the electrical system,
if you have to manually switch the compressor on. Again, not a real
problem though.
As for relays. I don't know what the other person used, but I ended up
buying 2 of them. I went through a Bosch catalog and found a nice mini
relay, rated at 40 to 50 A on the contacts. This should be more than
enough as Terry only has a 20A fuse in the main power line to the compressor.
None of the auto parts store had "Bosch" relays. But one had a cross ref.
from Bosch to GP Sorensen (which they stocked). The original relay I wanted
they didn't cross, however, in that family of relays, they did have a cross
ref. to a MR38. The only drawback to this relay, is that it has both a
Normally Open and a Normally Closed contact (SPDT), and NO mounting tab. All
we really need for this is a SPST relay. But it was the 1st one I'd been
able to find so I paid the outlandish price of $13 for it.
I've been to Radio Shack several looking for a relay to no avail. However,
the day after I purchase the MR38, I was in Radio Shack (to purchase the
despiking diodes) and they had an equivilant relay (same pin out, and a
SPST) that can handle about 30A and has a mounting tab for $5 (much more
reasonable). So I bought one of them also.
My next problem was finding someplace that sold sockets for the relays.
I tried all the auto parts store - they all said to go to a junk yard and
cut one off of a car. I finally found a "Fleet Supply" house in town that
had the socket. It wasn't bad $6. It's a Federal Mogul 9185. It doesn't
have any mounting tabs either. I think I'm going to use a wire tie and
mount the relay and socket to the vertical support for the front of the
hood extension.
So progress, while slow is made. I guess the next step is to plumb in all
the air line.
A short note, the magazines are at the mailers now, so they should be at
our houses in about 2 weeks or less - hopefully.
John
John T. Blair WA4OHZ email: jblair@exis.net
Va. Beach, Va Phone: (757) 495-8229
48 TR1800 48 #4 Midget 65 Morgan 4/4 Series V
75 Bricklin SV1 77 Spitfire 71 Saab Sonett III
65 Rambler Classic
Morgan: www.team.net/www/morgan
Bricklin: www.bricklin.org
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