Wes,
By ohm's law your arithmetic seems to work well. Of course ohms law works best under DC conditions and your looking to put a switch in front of a reactive load. There is a substantial and momentary voltage increase as the field in the transformer coil is first established and again when it collapses.
So whats the answer? Well Id try the relay contacts you suggested, but in the back of my head I'd always be ready for it to fail.
Perhaps we can find someone else who can help calculate the induced load when the contacts make and break. Its an interesting question.
If no one jumps in perhaps by next weekend I can find some time to research an accurate answer.
The Leach amp is a neat project. A long time ago I helped a friend build 4 channels of Low TIM -4 for his PA system. They would have made good entries into the ugly amp thread, but hey, most of the time they worked.
(Has any one else ever seen a Brighten Sound "Loud Amplifier"? Not really related to the Low TIM-4, but rumored I think to be the precursor to the Ashly MosFet amps)
This is I think my last link related to the GE RR-7 latching contactor. It has lots of diagrams and applications:
http://www.geindustrial.com/products/applications/tlc/tlclvrc.pdf?SMSESSION=NO
By ohm's law your arithmetic seems to work well. Of course ohms law works best under DC conditions and your looking to put a switch in front of a reactive load. There is a substantial and momentary voltage increase as the field in the transformer coil is first established and again when it collapses.
So whats the answer? Well Id try the relay contacts you suggested, but in the back of my head I'd always be ready for it to fail.
Perhaps we can find someone else who can help calculate the induced load when the contacts make and break. Its an interesting question.
If no one jumps in perhaps by next weekend I can find some time to research an accurate answer.
The Leach amp is a neat project. A long time ago I helped a friend build 4 channels of Low TIM -4 for his PA system. They would have made good entries into the ugly amp thread, but hey, most of the time they worked.
(Has any one else ever seen a Brighten Sound "Loud Amplifier"? Not really related to the Low TIM-4, but rumored I think to be the precursor to the Ashly MosFet amps)
This is I think my last link related to the GE RR-7 latching contactor. It has lots of diagrams and applications:
http://www.geindustrial.com/products/applications/tlc/tlclvrc.pdf?SMSESSION=NO
Dave,
I believe this will answer Your question:
Agilent (former Hewlett Packard) AN-1399.pdf Application Note: Maximizing the Life Span of Your Relais
or searche google for: switching inductive loads
Additionally to a snubber circuit as described in the article I would use a soft start circuit (resistor shorted with a time delayed relais) for the amp. This would further help to reduce stress on the relais (and also this avoids to trip Your fuse eventually, when switching big toroid transformers) . Search the forum - I believe there are threads with schematics about soft starts.
Da5id4Vz,
I Highly DO NOT reccomend those GE latching switches for use in anything. In a past life when I used to service light dimming systems these relays always failed more then not. They are not cheap either. We usually replaced them with something else and never had to go back.
To keep relay contacts from eventually disentegrating one must put a snubber across the contacts. A .1uf at 1kv in series with a 10 ohm 1/2 watt flame proof resistor is a very safe way to make a snubber, and they are very effective in prolonging the life of the contacts.
Mark
I Highly DO NOT reccomend those GE latching switches for use in anything. In a past life when I used to service light dimming systems these relays always failed more then not. They are not cheap either. We usually replaced them with something else and never had to go back.
To keep relay contacts from eventually disentegrating one must put a snubber across the contacts. A .1uf at 1kv in series with a 10 ohm 1/2 watt flame proof resistor is a very safe way to make a snubber, and they are very effective in prolonging the life of the contacts.
Mark
Snubers!
But of course!
I had it in my mind that the relay should be overrated to account for the total current spike at make and break. Snubers are much friendlier to the neighbors’ radio reception too.
Mark, your GE RR-9 experience is interesting, thanks for passing it on. Do you know if it was the solenoid coils or the contacts that tended to fail? I suppose that for most applications I really prefer a solid state relay, but I find the latching nature of the RR9 appealing too.
But of course!
I had it in my mind that the relay should be overrated to account for the total current spike at make and break. Snubers are much friendlier to the neighbors’ radio reception too.
Mark, your GE RR-9 experience is interesting, thanks for passing it on. Do you know if it was the solenoid coils or the contacts that tended to fail? I suppose that for most applications I really prefer a solid state relay, but I find the latching nature of the RR9 appealing too.
Power Supply
Hi, as I'm am a rookie at this... does this mean that you get a bigger transformer then regulate the voltage down using IC's?
Does anyone have a source for info about how to design PSU? Or better yet a simple schematic of one they used for this circuit.
Sorry I know I'm kinda asking to be spoon fed here... At least until I get a little more experience.
Thanks,
-Wes
Hi, as I'm am a rookie at this... does this mean that you get a bigger transformer then regulate the voltage down using IC's?
Does anyone have a source for info about how to design PSU? Or better yet a simple schematic of one they used for this circuit.
Sorry I know I'm kinda asking to be spoon fed here... At least until I get a little more experience.
Thanks,
-Wes
I was talking about this schematic :
http://www.diyaudio.com/forums/attachment.php?s=&postid=68693
Which acts randomly when psu is turned on.
My idea is to use this schematic for quick muting on speakers using pulse switch button.
If the relay is turned on with the psu, i can hear the transcient noise of the psu on the speakers. But if the relay stays off, I can de-mute the amp with the button (whenever I want) and that's what I'd like each time
http://www.diyaudio.com/forums/attachment.php?s=&postid=68693
Which acts randomly when psu is turned on.
My idea is to use this schematic for quick muting on speakers using pulse switch button.
If the relay is turned on with the psu, i can hear the transcient noise of the psu on the speakers. But if the relay stays off, I can de-mute the amp with the button (whenever I want) and that's what I'd like each time
random state
Hello Johnix,
This circuit should allways be under power supply (in stand by)
to avoid random operation.
You can use any small transformer that you can get with the
reasonable seccondary voltage.
Also it is very important to use stabilided power supply (LM 7809).
Best regards,
Kristijan
Hello Johnix,
This circuit should allways be under power supply (in stand by)
to avoid random operation.
You can use any small transformer that you can get with the
reasonable seccondary voltage.
Also it is very important to use stabilided power supply (LM 7809).
Best regards,
Kristijan
Is it just possible to have a non-random behaviour on a CMOS gate when the PSU is switched on ?
edit :
What about this one :
edit :
What about this one :
An externally hosted image should be here but it was not working when we last tested it.
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