12v Tranny and 12v relay question's, lets beat a dead horse!

[keithrick]

Hi Guys,

I have finally got my amp to where I want it and so know I getting ready to install relays. I am hoping to install three relays, Channel, Mid and Boost. I have been reading alot of the posts (Mats for instance- https://tubeamparchive.com/viewtopic.php?t=1146 and I have a few questions.

Parts I intend to use:

Rat Shack 6-0-6v .45a transformer
Mouser part# MR62-12usry DPDT relays, (3)
(2) 4700Uf
100VDC 1500ma Bridge rectifier
1N4007 diodes
Switchcraft 4 pin w/ ground xlr jack.

1. With a 12v transformer do you still need a 12V voltage regulator?

2. Do you still need to rectify the voltage? Won't that make it higher?

3. I have a 100VDC 1500MA rectifier could I use this or is it voltage dependant?

4. I intend to wire similiar to Mat's diagram in the thread listed above where the relay is wired just like the switches.

5. Can you mount the relays upside down or pin up to wire point to point? They do look pretty fragile.


I am pretty sure I can figure the rest out based upon Mat's drawings.

Thanks in advance for any answers!

If you have a cool layout or pics not posts and feel like sharing please feel free to email the to me at jzzmasrATComcast.Net

[glasman]

Hi Guys,

I have finally got my amp to where I want it and so know I getting ready to install relays. I am hoping to install three relays, Channel, Mid and Boost. I have been reading alot of the posts (Mats for instance- https://tubeamparchive.com/viewtopic.php?t=1146 and I have a few questions.

Parts I intend to use:

Rat Shack 6-0-6v .45a transformer
Mouser part# MR62-12usry DPDT relays, (3)
(2) 4700Uf
100VDC 1500ma Bridge rectifier
1N4007 diodes
Switchcraft 4 pin w/ ground xlr jack.

1. With a 12v transformer do you still need a 12V voltage regulator?

It is a nice idea, and the part is cheap, less than a buck for a 7812.

2. Do you still need to rectify the voltage? Won't that make it higher?

with the 12.6 volt tranny you will get about 16 volts rectified with a full wave bridge. As far as rectifying, the answer is yes, otherwise the relays will chatter. The other issue is noise. I really would not want to put a 12v AC 60 hertz signal that close to my signal path.

No I would say that 16 volts is not a good margine for a 7812. I use the 24.2 volts 450MA RS tranny in some amps (not my new ones). That little extra will always insure that I have 12V, no matter how many relays are engaged.

3. I have a 100VDC 1500MA rectifier could I use this or is it voltage dependant?

This should be fine. As I remember the rule of thumb is 3 : 1 PIV rating.

4. I intend to wire similiar to Mat's diagram in the thread listed above where the relay is wired just like the switches.

Yup,

5. Can you mount the relays upside down or pin up to wire point to point? They do look pretty fragile.

Dead Bug style is fine and I know several builders that do it all the time.

Good luck....

[glasman]

BTW, here is a short of my relay supply from a recent build.

[img:800:533]http://glaswerks.com/images/dc/Img_0096.jpg[/img]

Gary

[keithrick]

Thanks Gary! I am gonna try it out this weekend! I don't think it will look quite as neat as your wiring There might be a dead bug or two in my rats nest.

Keith

[skyboltone]

Keith:
1)Rectify then regulate, not the other way around.
2)You'll get no smoother filter particularly with the 4700 than with a 1000, at least when looked at on the PS modeling software we've all been using. The relay coils themselves will smooth things out a bit.
3)As has been stated, the transformer is too small current wise, I don't agree that you need a 24V to get the job done, but it's of no consiquence either way provided that your regulator can dump that much heat and voltage without letting the smoke out.
4)Using the bridge rectifier, not sure why you need the 1n4007s

I'm using a 5 volt winding on the PT, keeping it COMPLETELY isolated and regulating the 7 volt output back to 6 volts with a 7806 regulator. Skip uses this same approach I think. The 4 amp winding on the main PT will not sag with a half amp maximum of your relay load. At least that's what the modeling software says.

Dan
(Is that your's Gary?, I've lost track.)

[glasman]

Dan
(Is that your's Gary?, I've lost track.)

If you are talking about the amp picture, yes, it is my Rumplestiltclone I built a while back. I like that board so much that I used it in my new generation amps.


As as as the 1N4007. I bet that is something that someone saw on boards. I insert 2 4007's in the ground leg of the 7812 to raise the output of the regulator to 13.5v. I did this on amps that have the indicator LED on the footswitch in series with the coil winding. Makes for a nice bright LED.

I switched to low current relay now so I have to run a separate power wire to the footswitch.

FWIW, if you read the spec's on the 7800 regulators you will see they like to have about 5 volts headroom.

Gary

[keithrick]

Wow, You guys have been busy! I appreciate the help! Dan thanks for joining the thread as well.


Per Gary

No I would say that 16 volts is not a good margine for a 7812. I use the 24.2 volts 450MA RS tranny in some amps (not my new ones). That little extra will always insure that I have 12V, no matter how many relays are engaged

Per Dan

As has been stated, the transformer is too small current wise, I don't agree that you need a 24V to get the job done, but it's of no consiquence either way provided that your regulator can dump that much heat and voltage without letting the smoke out.

Now I am a little confused Is the crucial rating the voltage or the 450ma...or both. I know the relays operate at 8vdc and 400ma per the spec sheet. BTW these are non Latching.

Does this mean that only one could be engaged at a time? and...

Is the current draw constant or is it momentaty to engage the latch?

[glasman]

Wow, You guys have been busy! I appreciate the help! Dan thanks for joining the thread as well.


Per Gary

No I would say that 16 volts is not a good margine for a 7812. I use the 24.2 volts 450MA RS tranny in some amps (not my new ones). That little extra will always insure that I have 12V, no matter how many relays are engaged

Per Dan

As has been stated, the transformer is too small current wise, I don't agree that you need a 24V to get the job done, but it's of no consiquence either way provided that your regulator can dump that much heat and voltage without letting the smoke out.

Now I am a little confused Is the crucial rating the voltage or the 450ma...or both. I know the relays operate at 8vdc and 400ma per the spec sheet. BTW these are non Latching.

Does this mean that only one could be engaged at a time? and...

Is the current draw constant or is it momentaty to engage the latch?

OK I rechecked the 7812 specs, it requires 14.5 input to maintain 12 volts. So the 12.6V RS tranny should be fine. Sorry for bad information.

I also checked the specs on your relay (looks similar to the axicom's that I use).

MR62-12USRY 12v 360 ohm coil resistance

This relay should draw about 34ma under operation. Three of them would only be combined of around 100mA.

Gary

[skyboltone]

Dan
(Is that your's Gary?, I've lost track.)

If you are talking about the amp picture, yes, it is my Rumplestiltclone I built a while back. I like that board so much that I used it in my new generation amps.
Gary

No I'm talking about the Power Supply modeling software. Somebody on here owns it I think. It works great.

Nice trick on the 4007s and series LEDs. It had not occured to me. I'm going Mat's original route with the 9 volt battery and the current limiting resistor. That may change now.

Dan

[glasman]

Dan
(Is that your's Gary?, I've lost track.)

If you are talking about the amp picture, yes, it is my Rumplestiltclone I built a while back. I like that board so much that I used it in my new generation amps.
Gary

No I'm talking about the Power Supply modeling software. Somebody on here owns it I think. It works great.

Nice trick on the 4007s and series LEDs. It had not occured to me. I'm going Mat's original route with the 9 volt battery and the current limiting resistor. That may change now.

Dan

I use Duncan's power supply modeling program, its free and easy to use.

Here is a schematic of one way to implement the LED's. With 13.5 volts, you eliminate the zener.

[img:777:435]http://www.glaswerks.com/schematics/sodfootswitch.jpg[/img]

Gary

[skyboltone]

Thanks Gray;
For the scheme and the answer. Duncan, Duncan, Duncan.


Dan

[glasman]

Thanks Gray;
For the scheme and the answer. Duncan, Duncan, Duncan.


Dan

Duncan Duncan Duncan... Great Amp resource page.

http://www.duncanamps.com/

His software page. Highly recommended viewing!!

http://www.duncanamps.com/software.html


And the power supply designer page, I use this program on every project. Saves a lot of time and it is extremely accurate.

http://www.duncanamps.com/psud2/index.html

Gary