Started a ODS

[heisthl]

RadioShack should carry the 7805, if not they can order it for you - no shipping charges.

[tonejunkie]

It is only a online item. I called a Radio Shack store and they said they charge shipping to the store if it is only a online item. Oh Well. I'll probobly just have to bite the bullet and place another mouser order today. Thanks TJ

[fp2000]

I got one from radio shack that I did not use. I can send it to you via regular mail for free if you want. It doesn't weigh much so I should take a 39 cent stamp. PM me if you're interested.

[tonejunkie]

I fired her up and the clean channel is great!! I initially had pretty bad noise but when I grounded the 5v relay supply to the chassis the noise was gone. I do have a problem with the relay switching.

The relay board is exaclty like the one Bob-I gave me in the previous reply. The 5v heaters are giving me 5vac, after the bridge we are getting a little over 5vdc but after the 5v regulator I am getting 3.9vdc. What would be your first step in trouble shooting this? Do you think it is the reglulator? The 3.9 does not change when I change the ground from floating to chassis grounded. It also does not change when I flip the switches to trip the relay (which does not get tripped due to the low voltage availible?). What do you think.

I would have a pic but my wife went to LA and took the camera.

[glasman]

The 5V regulator will need at least 8v to work correctly. If you are only using it for your relays, I would dump the regulator and just used a pretty large filter cap on the 5V dc. Relays are pretty forgiving.

Gary

[fabiomayo]

I'm interested in this since I plan to use Bob-I's schematic.

Shouldn't the relay work properly even within 75% of the rated voltage (i.e. 3.75v)?

Also, the specs for my relays seems to indicate AC can be used safely, although
it might shorten it's life. Is there any problem in doing that?
Life would be much easier, wouldn't it?

[tonejunkie]

Is 1000uf enough capacitance? Or should I use 4700uf? Thanks Glass

Also the spec sheet on the omron 5v relays says that the must turn on is 70% of rated voltage which 3.5. I wonder why it is not working. Probobly user error. I will check it again.

[tonejunkie]

I have taken the regulator out. I am getting around 6vdc on the relays but still no switching. I am testing this with no tubes in the amp just testing for a cange in continuity between the pins of the relay but there is no change. Maybee I have a concept screwed up. when the relay is off there is no ground on the coil of the relay and we turn it on by grounding the coil. The gounding is on the anode of the diode of the relay board. Any ideas? Thanks TJ

[fabiomayo]

You're correct. You connect the voltage supply to one side of the coil and
keep the other side lifted from ground. That way the switch pins will be
connected in the normally closed pos. When you ground the coil, you
activate the relay and common switch pins connect to normally open pins.

It doen's matter which side of the coil you supply voltage or ground - without
a diode, that is. With a diode, I have no idea! Let's hope someone
else chimes in... I'll be checking...

All the best.

[tonejunkie]

User error for sure . I assumed the layout of the relay was a certain way and of course it was not. The channel switching works to profection. I am also very happy with the noise floor of the amp, I think it's my quietest yet. I will get a sample up in the next couple of days in a new thread. I would love some help tweaking the amp. Thanks for all the help in this thread (and others). I especially thank Bob-I, T-dale, Glassman and Normster (for his great layout).

I built a dumble clone! Sweet