Relay
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Posts: 46,084
Just my little bit... I used to put a NE2 neon lamp across the coil being
fed AC to kill the spikes. This works if the coil voltage is less than 90
volts AC, like 24VAC. The lamp would conduct the spike and kill it. For
higher voltages I put two in series, good for 120VAC. Never lost a Triac.
James R. Parish
J-Tech Internet Services
J-Com Enterprises, Inc.
Original Message
From: Steve Wilke [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=KgkSoqbJVDYpCuMT_HcmYZoVMkizFaWXNRhoDIP6xV8U8f76Axy5CXbXRlm5vm-A7vAKDI7Iz1SPcKqBT-iyyfU]slwilke@t...[/url
Sent: Friday, October 05, 2001 9:26 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Relay "shunt resistor"; was Short Circuit
Protection
Mark,
I wasn't quite "with it" yesterday, and didn't think your question through
completely.
A "clamping" or "wheel" diode across a relay's coil works great *IF* the
voltage applied to the coil is DC. However, this won't do for AC, as the
clamping/wheel diode would present a dead short to ground for 1/2 off the
cycle (when the AC voltage went negative).
For this reason, in AC circuits only, you must use a shunt resistor across
the relay's coil (or other inductive load).
Original Message
From: Mark Adams [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=3Omm5eg86ggZVjVMlx-z60sOFG1PstcIi5n_dk3SRlxA3Kv_q0rh5DRaIwyvAgJXnhMWtr-nycc]madams@a...[/url
We were looking at some BOSCH relays and they listed an option that
included a 'shunt resistor' and the ones we currently purchase with an
included diode. Now, the question is why is the shunt resistor there?
<snip>
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fed AC to kill the spikes. This works if the coil voltage is less than 90
volts AC, like 24VAC. The lamp would conduct the spike and kill it. For
higher voltages I put two in series, good for 120VAC. Never lost a Triac.
James R. Parish
J-Tech Internet Services
J-Com Enterprises, Inc.
Original Message
From: Steve Wilke [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=KgkSoqbJVDYpCuMT_HcmYZoVMkizFaWXNRhoDIP6xV8U8f76Axy5CXbXRlm5vm-A7vAKDI7Iz1SPcKqBT-iyyfU]slwilke@t...[/url
Sent: Friday, October 05, 2001 9:26 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Relay "shunt resistor"; was Short Circuit
Protection
Mark,
I wasn't quite "with it" yesterday, and didn't think your question through
completely.
A "clamping" or "wheel" diode across a relay's coil works great *IF* the
voltage applied to the coil is DC. However, this won't do for AC, as the
clamping/wheel diode would present a dead short to ground for 1/2 off the
cycle (when the AC voltage went negative).
For this reason, in AC circuits only, you must use a shunt resistor across
the relay's coil (or other inductive load).
Original Message
From: Mark Adams [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=3Omm5eg86ggZVjVMlx-z60sOFG1PstcIi5n_dk3SRlxA3Kv_q0rh5DRaIwyvAgJXnhMWtr-nycc]madams@a...[/url
We were looking at some BOSCH relays and they listed an option that
included a 'shunt resistor' and the ones we currently purchase with an
included diode. Now, the question is why is the shunt resistor there?
<snip>
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/