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| Author |
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DaveM
electronics forum Guru Wannabe
Joined: 04 May 2005
Posts: 297
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 Posted: Wed May 31, 2006 6:46 pm Post subject:
Re: Anyone know of a good cheap relay for 120VAC needing low coil power
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<mike_l_rossREMOVE@REMOVEsbcglobal.net> wrote in message
news:X75fg.88483$H71.86022@newssvr13.news.prodigy.com...
| Quote: | I'm trying to use my little AVR to control up to 12 120VAC loads, up to 5
amps. Does anyone know of a cheap (< $5 US) relay (SPST-NO) that only
needs 40 mA or less to activate? My Tyco T77 relays need 90 mA at 5VDC to
pull in the contacts, it turns out, so the processor dies. The lowest I've
found on-line is 60 mA. I don't have a harsh environment, or rapid
switching requirements, just need a simple on-off relay. I'm switching
banks of lights, should look cool if I can get it to work. Thanks for any
advice.
Mike Ross
--
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I don't think you need low power relays... your money would be better spent on a
proper interface between the AVR port and the relays. A simple transistor
between the AVR output and the relay would let you use your existing relays and
would amount to a few cents per relay.
You didn't indicate whether the AVR output is high or low when the relay should
turn on, so first, I'll assume that it's low. In that case, use a PNP
transistor (such as a 2N2907). Connect it as such:
Please view in a fixed-width font such as Courier.
+----------+ +5V
| | |
| | |
| AVR | |
| | |
| | |
| | | E
| | 10K /
| | +------+ |/
| +--------+ +------| 2N2907
| | +------+ B |\
| | \
| | |C
| | |
| | |
| | +-+-+
| | | |
| | | |
| | | | Relay coil
| | | |
| | | |
| | +-+-+
| | |
| | |
| | --+--
| | ---
| | -
+----------+
In case the AVR output is high when the relay should be on,
use an NPN transistor (such as a 2N2222) like this:
+5V
|
|
+-+-+
| |
+----------+ | |
| | | | Relay coil
| | | |
| AVR | | |
| | +-+-+
| | |
| | |C
| | 10K /
| | +------+ |/
| +--------+ +------| 2N2222
| | +------+ B |\
| | \
| | |E
| | |
| | |
| | --+--
| | ---
| | -
| |
+----------+
Total cost per output: about $0.50 US
Cheers!!!!
--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)
Some days you're the dog, some days the hydrant. |
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Brian
electronics forum Guru
Joined: 02 May 2005
Posts: 323
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| Posted: Thu Jun 01, 2006 4:29 am Post subject:
Re: Anyone know of a good cheap relay for 120VAC needing low coil power
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<mike_l_rossREMOVE@REMOVEsbcglobal.net> wrote in message
news:X75fg.88483$H71.86022@newssvr13.news.prodigy.com...
| Quote: | I'm trying to use my little AVR to control up to 12 120VAC loads, up to 5
amps. Does anyone know of a cheap (< $5 US) relay (SPST-NO) that only
needs 40 mA or less to activate? My Tyco T77 relays need 90 mA at 5VDC to
pull in the contacts, it turns out, so the processor dies. The lowest I've
found on-line is 60 mA. I don't have a harsh environment, or rapid
switching requirements, just need a simple on-off relay. I'm switching
banks of lights, should look cool if I can get it to work. Thanks for any
advice.
Mike Ross
--
|
You might want to use a MOSFET (like a 2N7000) to drive the relays. Or maybe
a Darlington array, something like the ULN-2803A. This would be easier on
the AVR and also make the relay selection less fussy.
Brian |
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Brian
electronics forum Guru
Joined: 02 May 2005
Posts: 323
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| Posted: Thu Jun 01, 2006 2:15 pm Post subject:
Re: Anyone know of a good cheap relay for 120VAC needing low coil power
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<mike_l_rossREMOVE@REMOVEsbcglobal.net> wrote in message
news:X75fg.88483$H71.86022@newssvr13.news.prodigy.com...
| Quote: | I'm trying to use my little AVR to control up to 12 120VAC loads, up to 5
amps. Does anyone know of a cheap (< $5 US) relay (SPST-NO) that only
needs 40 mA or less to activate? My Tyco T77 relays need 90 mA at 5VDC to
pull in the contacts, it turns out, so the processor dies. The lowest I've
found on-line is 60 mA. I don't have a harsh environment, or rapid
switching requirements, just need a simple on-off relay. I'm switching
banks of lights, should look cool if I can get it to work. Thanks for any
advice.
Mike Ross
--
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You might be better off using transistors, mosfets (like a 2N7000) or a
Darlington array (like a ULN-2803A) to drive the relays. It would be easier
on the AVR and it would probably be easier to find lower priced relays.
Brian |
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Ross Herbert
electronics forum Guru
Joined: 03 May 2005
Posts: 429
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| Posted: Sat Jun 17, 2006 5:02 am Post subject:
Re: very high current DC switch
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On Sat, 17 Jun 2006 03:54:59 GMT, Roy L. Fuchs
<roylfuchs@urfargingicehole.org> wrote:
| Quote: | On Thu, 15 Jun 2006 10:34:58 -0000, Jasen Betts <jasen@free.net.nz
Gave us:
On 2006-06-14, Chris W <1qazse4@cox.net> wrote:
Does anyone know where I can get a reasonably priced ($30 or less)
switch that can handle at least 200 amps at 13.8V?
maybe an old starter switch (from before solenoids/relays were used)
http://205.243.100.155/frames/Newgap2a.jpg
Hahahahaahahahaa! Thousands of Amps!
|
I'd like to see those contacts after they tried to break a motor
circuit carrying 100A DC - the return spring looks very weak... not
exactly a rapid action. |
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Lostgallifreyan
electronics forum Guru Wannabe
Joined: 13 Apr 2006
Posts: 241
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| Posted: Tue Jul 04, 2006 4:05 am Post subject:
Re: help me please !!!
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diplome333@hotmail.com wrote:
Yep. I can safely agree, you have a problem. |
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David L. Jones
electronics forum Guru Wannabe
Joined: 07 Jun 2005
Posts: 286
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| Posted: Thu Jul 06, 2006 3:24 am Post subject:
Re: Quality Manager needed : Full Time : near south of Los Angeles - CA
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gitproinc@yahoo.com wrote:
| Quote: | Quality Manager needed on Full Time basis near south of Los Angeles -
CA
A. Must have a Bachelor in Engineering and experience in hard floor
production management
B. Degree or diploma in Statistical quality control
C. Must have idea of some these regulations :-
ISO9002, CSA, ATEX, EC Directives, FDA regulations
Our client is one of the world's most reputed instrumentation company
with $1B+ global revenue. Their US division is in Anaheim, California.
Occasional international and national travel is required.
reply to recruiter@gitpro.com
or contact
Sree
GITPRO INC.
Cell : (901) 339-9838
Fax : (413) 725-3576
|
You forgot another requirement:
- Must be willing to work for someone stupid enough to post to the
wrong newsgroups.
Dave  |
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GB
electronics forum beginner
Joined: 27 Jun 2006
Posts: 4
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| Posted: Thu Jul 06, 2006 8:57 am Post subject:
Re: Quality Manager needed : Full Time : near south of Los Angeles - CA
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"David L. Jones" <altzone@gmail.com> wrote in news:1152156272.553938.238250
@j8g2000cwa.googlegroups.com:
| Quote: | gitproinc@yahoo.com wrote:
Quality Manager needed on Full Time basis near south of Los Angeles -
CA
[...]
Our client is one of the world's most reputed instrumentation company
with $1B+ global revenue. Their US division is in Anaheim, California.
Occasional international and national travel is required.
You forgot another requirement:
- Must be willing to work for someone stupid enough to post to the
wrong newsgroups.
|
Er, must be wiling to work for someone stupid enough to hire someone
from a pimp who's stupid enough to post to the wrong newsgroup.
GB, my bullshit detector tells me that the post is from a pimp, not
an actual employer. Truth be known the job doesn't even exist.
--
"Men will never be free until the last king is strangled with the
entrails of the last priest." (Diderot, paraphrasing Meslier) |
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David L. Jones
electronics forum Guru Wannabe
Joined: 07 Jun 2005
Posts: 286
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| Posted: Thu Jul 06, 2006 10:07 am Post subject:
Re: Quality Manager needed : Full Time : near south of Los Angeles - CA
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GB wrote:
| Quote: | "David L. Jones" <altzone@gmail.com> wrote in news:1152156272.553938.238250
@j8g2000cwa.googlegroups.com:
gitproinc@yahoo.com wrote:
Quality Manager needed on Full Time basis near south of Los Angeles -
CA
[...]
Our client is one of the world's most reputed instrumentation company
with $1B+ global revenue. Their US division is in Anaheim, California.
Occasional international and national travel is required.
You forgot another requirement:
- Must be willing to work for someone stupid enough to post to the
wrong newsgroups.
Er, must be wiling to work for someone stupid enough to hire someone
from a pimp who's stupid enough to post to the wrong newsgroup.
|
Doh, of course!
| Quote: | GB, my bullshit detector tells me that the post is from a pimp, not
an actual employer. Truth be known the job doesn't even exist.
|
It is indeed from a pimp. Good to see they are at least trying to do
something for their measly 25% of your first years salary commission. I
live in eternal hope that one day I'll actually meet a "recruitment
consultant" that actually has a clue. I'll settle for half a clue, but
alas I just don't think it's obtainable.
Dave |
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JeffM
electronics forum Guru
Joined: 02 May 2005
Posts: 1007
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| Posted: Mon Jul 17, 2006 2:31 am Post subject:
abuse@newsfeeds.com
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was: Cell Phone Information Site
Chris wrote:
>[SPAM[ |
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Ross Herbert
electronics forum Guru
Joined: 03 May 2005
Posts: 429
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| Posted: Tue Jul 18, 2006 4:15 am Post subject:
Re: Quick stupid question: difference between 2n222 and 2n222a transistors?
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On Mon, 17 Jul 2006 22:16:50 -0500, "Eric Schmitt"
<erics.pinball@gmail.com> wrote:
| Quote: | are there a difference between the two?
2n222
2n222a
can they be interchanged?
please send me a direct e mail,
thanks for reading!!
--Eric
|
I think you mean 2N2222...
From memory the 2N2222 (TO18) has Vceo=30V and the A version has
Vceo=40V. Therefore, you can use the A version in place of the 2222
but not necessarily the other way round. If Vce supply voltage is less
than 30V then either will do. |
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Ken
electronics forum beginner
Joined: 15 May 2005
Posts: 15
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| Posted: Tue Jul 18, 2006 11:14 am Post subject:
Re: Quick stupid question: difference between 2n222 and 2n222a transistors?
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On Mon, 17 Jul 2006 22:16:50 -0500, "Eric Schmitt"
<erics.pinball@gmail.com> wrote:
| Quote: | are there a difference between the two?
|
Transistor 2N2222
Higher voltage capacity for the A version.
http://www-micrel.deis.unibo.it/DATA_SHEETS/2N2222_CNV_2.pdf
| Quote: | can they be interchanged?
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You can allways change to A version. |
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