postpunk, if you do it right a LM3886 (like my designs) is totally click and thump free so if you do have problems AND has made the connection of the LM3886 right including the mute, then you have bumps coming from the preamp or you get a switch-off transient from the mains switch which (the transient) is coupled through the transformer and/or the wiring. A neat and tidy wiring may have it's advantages. One hint is to separate the mains circuitry with the secondary as much as possible.
... so your solution is...?
Hi Nuuk
You wrote in your homepage:
Why are you not sure about the originator of the idea? My name is clearly stated in your first posting in this thread, so don't worry to mention me!
BTW: A nice idea is to connect a "power up" LED in parallel to the relay (for example a green
LED).
And another LED (for example a red LED) between ground an pin 3, as there is a voltage during the delay.
This way, the red one is showing you the delay is working, the green shows operational status.
Have fun!
Franz
You wrote in your homepage:
Why are you not sure about the originator of the idea? My name is clearly stated in your first posting in this thread, so don't worry to mention me!
BTW: A nice idea is to connect a "power up" LED in parallel to the relay (for example a green
LED).And another LED (for example a red LED) between ground an pin 3, as there is a voltage during the delay.
This way, the red one is showing you the delay is working, the green shows operational status.
Have fun!
Franz
Hi Franz,
Yes, I know it was you who did that diagram but I had seen the idea on this forum a long time before you put your diagram in another thread. So I didn't want to credit you with the idea and risk offending somebody else!
This can be a tricky place to avoid offending somebody and hope that, so far, I have steered a safe course!
Yes, I know it was you who did that diagram but I had seen the idea on this forum a long time before you put your diagram in another thread. So I didn't want to credit you with the idea and risk offending somebody else!
This can be a tricky place to avoid offending somebody and hope that, so far, I have steered a safe course!
Hi Nuuk
Sorry, it is not so important.
The idea to ground the input of an solid state power amp for delay is old and not born in this forum.
And the schematics you used, is originating from me, not my invention too, I agree, just the result of reading the datasheet of timer chips and implementing it.
Franz
Sorry, it is not so important.
The idea to ground the input of an solid state power amp for delay is old and not born in this forum.
And the schematics you used, is originating from me, not my invention too, I agree, just the result of reading the datasheet of timer chips and implementing it.
Franz
Hi,
Q1.
how quickly does this 555 circuit drop out on loss of power?
instant+relay drop out time <10mS?
or
1 or 2mS+relay drop out time <=12mS?
or
something longer?
The DC supply could be half wave rectified from one transformer tapping.
Q2.
How much smoothing is required to give reliable relay pull in?
and
Q3.
how does one calculate how quickly the smoothing discharges enough to let the 555+relay drop out?
Or,
Q4.
is it all done by trial and error on a plugboard?
If so, then
Q5.
how does one measure the delay?
finally,
Q6.
is the diode between V+ and pin4 required?
Q1.
how quickly does this 555 circuit drop out on loss of power?
instant+relay drop out time <10mS?
or
1 or 2mS+relay drop out time <=12mS?
or
something longer?
The DC supply could be half wave rectified from one transformer tapping.
Q2.
How much smoothing is required to give reliable relay pull in?
and
Q3.
how does one calculate how quickly the smoothing discharges enough to let the 555+relay drop out?
Or,
Q4.
is it all done by trial and error on a plugboard?
If so, then
Q5.
how does one measure the delay?
finally,
Q6.
is the diode between V+ and pin4 required?
Is there any other way?
Well that's the way I got mine working Andrew.Is Q5 a trick question? If not, then I will tell you that I use a stop-watch!
I run mine from the positive rail of the supply that I use for the pre amp, buffer, or filter circuit.
Not sure about the diode question. I just followed the circuit and included one anyway.
Hi Nuuk,
thanks for keeping in touch on this old thread.
The timed pull in delay can be calculated and if need be measured.
It's the drop out delay on power off that I am interested in.
I know that the relay manufacturer will quote a delay for drop out of 2 to 10mS is fairly common, but how long for the circuit to remove coil drive and how long for the rectifier & minimal smoothing to remove supply. These I suspect are significant and I know from my system at present I need much less than 1second to protect the downstream components.
No trick in the question, any of them.
thanks for keeping in touch on this old thread.
The timed pull in delay can be calculated and if need be measured.
It's the drop out delay on power off that I am interested in.
I know that the relay manufacturer will quote a delay for drop out of 2 to 10mS is fairly common, but how long for the circuit to remove coil drive and how long for the rectifier & minimal smoothing to remove supply. These I suspect are significant and I know from my system at present I need much less than 1second to protect the downstream components.
No trick in the question, any of them.
Hi Andrew. I didn't really think that a chap of your calibre would be posing a trick question.
So it is not the time that the relay takes to switch on that you want to know, but actually how fast the contacts open and close. Is that right?
If so could you explain how that is relevant in this application? I understand in the case of something like a speaker protection circuit how the speed of the relay could be crucial, but not in the two situations that I have used the delay circuit in, ie for temporarily shorting the output of a buffer/pre amp etc, or creating a 'soft start' for a class-T amp.
So it is not the time that the relay takes to switch on that you want to know, but actually how fast the contacts open and close. Is that right?
If so could you explain how that is relevant in this application? I understand in the case of something like a speaker protection circuit how the speed of the relay could be crucial, but not in the two situations that I have used the delay circuit in, ie for temporarily shorting the output of a buffer/pre amp etc, or creating a 'soft start' for a class-T amp.
Hi,
I am in the country fed from a single three phase supply on poles.
We (the community) suffer irregular (but often) brown outs and total failure lasting just a few tenths of seconds to a few seconds and less often total failure stretching to hours. My computer is on uninteruptible supply.
To compound the problem, when power is restored it can sometimes chatter (some auto switch pulling out maybe?) over a second on two.
I have one pre-amp I cannot use at present. It is single ended and has NO ELECTROLYTICS, so PSU capacitance is fairly low. On drop out of power it sends an enormous "crack" to the speakers. I can control switch on if I do it manually but I cannot control power drop out nor auto switch on if I am not present to save my speakers.
Thermistor soft start is no good to me!!
Similarly, I need to think through the auto start up sequence and timings to allow all my equipment to safely start up and shut down without "thinking" (possibly including a latch for some parts).
When I have solved the power down sequencing problem, I can bring my favorite pre-amp back into the system.
Speed of muting on drop out seems to be crucial to my system.
I am in the country fed from a single three phase supply on poles.
We (the community) suffer irregular (but often) brown outs and total failure lasting just a few tenths of seconds to a few seconds and less often total failure stretching to hours. My computer is on uninteruptible supply.
To compound the problem, when power is restored it can sometimes chatter (some auto switch pulling out maybe?) over a second on two.
I have one pre-amp I cannot use at present. It is single ended and has NO ELECTROLYTICS, so PSU capacitance is fairly low. On drop out of power it sends an enormous "crack" to the speakers. I can control switch on if I do it manually but I cannot control power drop out nor auto switch on if I am not present to save my speakers.
Thermistor soft start is no good to me!!
Similarly, I need to think through the auto start up sequence and timings to allow all my equipment to safely start up and shut down without "thinking" (possibly including a latch for some parts).
When I have solved the power down sequencing problem, I can bring my favorite pre-amp back into the system.
Speed of muting on drop out seems to be crucial to my system.
sometimes it's the only way to get a discussion jump started or to extract the required response.I didn't really think that a chap of your calibre would be posing a trick question.
Well your electronics knowledge is far in advance of mine.
But the circuit is simple and inexpensive and I wonder if you could try it with your pre-amp, a spare amp and some test speakers. You could turn it all on and off at the mains to see if you get that nasty noise when the power comes back on.
Not very scientific but should give you the information that you need.
But the circuit is simple and inexpensive and I wonder if you could try it with your pre-amp, a spare amp and some test speakers. You could turn it all on and off at the mains to see if you get that nasty noise when the power comes back on.
Not very scientific but should give you the information that you need.
Hi Nuuk,
I built up a plug board with your delay mute circuit.
I used a 9V battery, so no smoothing experiments yet.
I omitted the extra diode between pin4 and the relay, but kept the diode//relay to catch back emf from the coil when it gets de-energised.
Two things I have found
1. it drops out fairly quickly, I can't measure it but I guess quite a bit less than 500mS.
Any thoughts on measuring the time from power off to relay closed?
2. the delay resets and times again no matter how short I try to make the power off period. This is a good feature, muting on chattering mains when the auto closer keeps retrying to make that power on connection for all us consumers.
Next, it's the small transformer and minimal smoothing, to see what happens.
I built up a plug board with your delay mute circuit.
I used a 9V battery, so no smoothing experiments yet.
I omitted the extra diode between pin4 and the relay, but kept the diode//relay to catch back emf from the coil when it gets de-energised.
Two things I have found
1. it drops out fairly quickly, I can't measure it but I guess quite a bit less than 500mS.
Any thoughts on measuring the time from power off to relay closed?
2. the delay resets and times again no matter how short I try to make the power off period. This is a good feature, muting on chattering mains when the auto closer keeps retrying to make that power on connection for all us consumers.
Next, it's the small transformer and minimal smoothing, to see what happens.
It's a wild guess on my part but if you could somehow hook the delay up to a PC, you could possibly time it like that.
That's consistent with what I have found here. I live in a seaside town with three (very) local amusement arcades. They often run more stuff than they should and we get 'blips' in our supply. I have yet to hear any problems when my systems have come back on, even after the shortest blip where all I notice is the light flashing once.
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