Hello,
I'd like to build a switch to plug my HiFi preamp and HC Preamp to my power amplifier.
As my HC preamp has a 12V trigger out, I think that it should be possible to use a 12V relay activated with this trigger. Am I right ?
I'm not really skilled with an iron, so I'd rather purchase an assembled board
I've seen for example this board, do you think it could suit my project ?
eBay | DPDT Signal Relay Module, 12Vdc, TAKAMISAWA RY12W-K Relay. Has Assembled.
I don't really understand the power / control part though. I thought this relay power by 12V switch to NO, and when not powered stays on NC. So what is the control input on this board for ?
Thank you for your advices
I'd like to build a switch to plug my HiFi preamp and HC Preamp to my power amplifier.
As my HC preamp has a 12V trigger out, I think that it should be possible to use a 12V relay activated with this trigger. Am I right ?
I'm not really skilled with an iron, so I'd rather purchase an assembled board
I've seen for example this board, do you think it could suit my project ?
eBay | DPDT Signal Relay Module, 12Vdc, TAKAMISAWA RY12W-K Relay. Has Assembled.
I don't really understand the power / control part though. I thought this relay power by 12V switch to NO, and when not powered stays on NC. So what is the control input on this board for ?
Thank you for your advices
Good news and bad news.
"...
Power Supply: 12V DC / 30mA (relay ON).
Input control signal voltage:
0V - 0.5V Low stage (relay is OFF),
0.5V – 2.5V (unknown state).
2.5V - 24V High state (relay is ON).
Input control signal high state current:
2.5V: 0.1mA
5V: 0.35mA
12V: 1.1mA
20V: 1.9mA
..."
Good news:
Suggests that the relay will be on with an input of 2.5V to 24V and at 12V input will draw 1.1mA from the "signal" source and 30mA from the power supply to power the relay.
The relay has both NC and NO contacts. (DPDT or 2PDT or 2 form C)
However
Bad news:
The relay contacts are only rated for 0.5A at 120VAC resistive.
This means at most a 60W bulb per contact.
Probably not good enough for an amplifier.
Close but no cigar.
Keep looking.
"...
Power Supply: 12V DC / 30mA (relay ON).
Input control signal voltage:
0V - 0.5V Low stage (relay is OFF),
0.5V – 2.5V (unknown state).
2.5V - 24V High state (relay is ON).
Input control signal high state current:
2.5V: 0.1mA
5V: 0.35mA
12V: 1.1mA
20V: 1.9mA
..."
Good news:
Suggests that the relay will be on with an input of 2.5V to 24V and at 12V input will draw 1.1mA from the "signal" source and 30mA from the power supply to power the relay.
The relay has both NC and NO contacts. (DPDT or 2PDT or 2 form C)
However
Bad news:
The relay contacts are only rated for 0.5A at 120VAC resistive.
This means at most a 60W bulb per contact.
Probably not good enough for an amplifier.
Close but no cigar.
Keep looking.
Thanks for your reply !
However I still have a few questions.
One basic to further my understanding of relays : what are the VCC (power signal) and INPUT (control signal) split in this board ? Can I use only the power signal ?
-> When my HC preamp is on (trigger send 12V) the relay switch on NO
-> WHen my HC peramp is off (trigger send 0V) the relay swith on NC
Second question : I don't want to power my amplifier, just send analog signal. Thus this will be low intensity signal right ? In this view won't the relay be enough ?
Last question : If not what do you think of the global schematic ? Can I use this board and plug another relay that would fit my needs ?
PS : Don't think it matters but I use 220V
However I still have a few questions.
One basic to further my understanding of relays : what are the VCC (power signal) and INPUT (control signal) split in this board ? Can I use only the power signal ?
-> When my HC preamp is on (trigger send 12V) the relay switch on NO
-> WHen my HC peramp is off (trigger send 0V) the relay swith on NC
Second question : I don't want to power my amplifier, just send analog signal. Thus this will be low intensity signal right ? In this view won't the relay be enough ?
Last question : If not what do you think of the global schematic ? Can I use this board and plug another relay that would fit my needs ?
PS : Don't think it matters but I use 220V
esp has given a few articles on remote starting and stopping.
Even triggered by the tiny audio signal.
I'm in the process of building a soft start with a power ON relay as well as the delay relay.
This suits a low voltage front panel (ON/OFF) switch rated for 12Vac/dc and also for a wire pair to remote equipment and through an overtemperature switch.
I am actually sending 12Vac around a switching circuit. If all are closed then the transformer secondary starts up the relays in sequence.
If any one switch goes open the amplifier relays both drop out, leaving just the 5VA with power (which has an F500mA fuse).
Even triggered by the tiny audio signal.
I'm in the process of building a soft start with a power ON relay as well as the delay relay.
This suits a low voltage front panel (ON/OFF) switch rated for 12Vac/dc and also for a wire pair to remote equipment and through an overtemperature switch.
I am actually sending 12Vac around a switching circuit. If all are closed then the transformer secondary starts up the relays in sequence.
If any one switch goes open the amplifier relays both drop out, leaving just the 5VA with power (which has an F500mA fuse).
Thank you for your answer.
Yet I think you've misunderstood my problem : I do not want to use the trigger to start or shut down anything
In fact I want to feed my amp with either the signal from my HiFi preamp, or from my HC preamp. To do that I need a switch which will choose which analog sinal to send to my amp.
The trigger is only my idea for choosing which signal to send. Usually, triggers are used to start amp, but here I thought of using it to choose HC signal over HiFi signal (which would be default position).
And my basic problem at this point is that I don't understand why a relay has to be powered and "signaled" (fed with a signal input). I thought powering it would make it switch positions.
If not I'll need to put a power in my switch, which would be a little overkill imo for what I want to do (prevent me from having to move my current switch manually ^_^)
Yet I think you've misunderstood my problem : I do not want to use the trigger to start or shut down anything
In fact I want to feed my amp with either the signal from my HiFi preamp, or from my HC preamp. To do that I need a switch which will choose which analog sinal to send to my amp.
The trigger is only my idea for choosing which signal to send. Usually, triggers are used to start amp, but here I thought of using it to choose HC signal over HiFi signal (which would be default position).
And my basic problem at this point is that I don't understand why a relay has to be powered and "signaled" (fed with a signal input). I thought powering it would make it switch positions.
If not I'll need to put a power in my switch, which would be a little overkill imo for what I want to do (prevent me from having to move my current switch manually ^_^)
You will have to read esp site for understanding certain basics.
In your case, you want priority for one source over the other. This is easy if each of the units give out some DC voltage, which will never be the case.
For constructing it with the audio signal, it will be difficult for you unless some readymade design is available. I doubt there is any.
Gajanan Phadte
In your case, you want priority for one source over the other. This is easy if each of the units give out some DC voltage, which will never be the case.
For constructing it with the audio signal, it will be difficult for you unless some readymade design is available. I doubt there is any.
Gajanan Phadte
Thanks for your answer.
I've read a website on relays (in french so giving you the link probably won't help), but I don't know esp. Do you have a link ?
I might not be able to do what I intend but at least I should learn more about relays
In fact here what I thought :
- relay when they are not powered, are on NC position
- when powered relays switch to NO position
- the relay doesn't contaminate the analog signal
Guess something isn't right there.
Yet this way would be perfect for me : the analog Hifi would be connected to NC and the HC to NO. For powering the switch I could use the 12V trigger out from my HC preamp (when the preamp is on it sends 12V).
I don't want to use the analog signal to control the switch.
It seems odd to me that nobody tought of this before. Mixing HiFi and HC is often an issue, and such a switch could be pretty handy.
I've read a website on relays (in french so giving you the link probably won't help), but I don't know esp. Do you have a link ?
I might not be able to do what I intend but at least I should learn more about relays
In fact here what I thought :
- relay when they are not powered, are on NC position
- when powered relays switch to NO position
- the relay doesn't contaminate the analog signal
Guess something isn't right there.
Yet this way would be perfect for me : the analog Hifi would be connected to NC and the HC to NO. For powering the switch I could use the 12V trigger out from my HC preamp (when the preamp is on it sends 12V).
I don't want to use the analog signal to control the switch.
It seems odd to me that nobody tought of this before. Mixing HiFi and HC is often an issue, and such a switch could be pretty handy.
If there is a 12 VDC output, then you will have to find out what current it can drive. If it can drive a relay, then buy a relay with good contacts for audio (gold is prefered).
You will need minimum 2 change over contacts. Four will be needed if you want to switch the ground.
If the 12VDC has no drive capability, then you will have to construct a simple circuit.
Gajanan Phadte
ESP site sound.westhost.com
You will need minimum 2 change over contacts. Four will be needed if you want to switch the ground.
If the 12VDC has no drive capability, then you will have to construct a simple circuit.
Gajanan Phadte
ESP site sound.westhost.com
Last edited:
Thank you, the website seems great
I've already found something realy close to what I want :
A-B Box For Amplifier Comparisons
I guess k1 and k2 are in fact only one relay of you use a DPDT.
If I remove the manual switch, I have exactly what I'm looking for. Do you agree ?
You're right, I need to know now if the trigger is enough to power the relay. What would be the right way ? Mesure how many AMpere it delivers ?
If the trigger cannot drive a relay, I'm not sure I'll keep on this project.
I've already found something realy close to what I want :
A-B Box For Amplifier Comparisons
I guess k1 and k2 are in fact only one relay of you use a DPDT.
If I remove the manual switch, I have exactly what I'm looking for. Do you agree ?
You're right, I need to know now if the trigger is enough to power the relay. What would be the right way ? Mesure how many AMpere it delivers ?
If the trigger cannot drive a relay, I'm not sure I'll keep on this project.
Thank you, the website seems great
...
You're right, I need to know now if the trigger is enough to power the relay. What would be the right way ? Mesure how many AMpere it delivers ?
If the trigger cannot drive a relay, I'm not sure I'll keep on this project.
Use a separate supply for the power for the relays...plug-in transformer.
It would such a pity to have to plug a dedicated power source for the switch, when my amp already provides 12VDC.
I couldn't find anything on the trigger out in my amp documentation, except that is is 12V (and that I've found on the net).
I've ordered the assembled relay on ebay. I'll plug my relay to VCC. At least I shoud be able to see if the trigger is enough to switch the relay...
I couldn't find anything on the trigger out in my amp documentation, except that is is 12V (and that I've found on the net).
I've ordered the assembled relay on ebay. I'll plug my relay to VCC. At least I shoud be able to see if the trigger is enough to switch the relay...
connect the trigger output via 100k load back to the trigger circuit ground.
Read off the voltage across the 100k.
Now swap the 100k to 10k and read voltage again.
Is the 10k Vdrop >= 90% of the 100k Vdrop?
If yes, then swap the 10k down to 1k.
Measure the Vdrop again.
Is the 1k Vdrop >= 80% of the 100k Vdrop?
Swap the 1k to 330r.
Measure the voltage again.
Is the 330r Vdrop >= 80% of the 100k Vdrop?
If yes, you are safe to drive a relay of >330r coil resistance.
Read off the voltage across the 100k.
Now swap the 100k to 10k and read voltage again.
Is the 10k Vdrop >= 90% of the 100k Vdrop?
If yes, then swap the 10k down to 1k.
Measure the Vdrop again.
Is the 1k Vdrop >= 80% of the 100k Vdrop?
Swap the 1k to 330r.
Measure the voltage again.
Is the 330r Vdrop >= 80% of the 100k Vdrop?
If yes, you are safe to drive a relay of >330r coil resistance.
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