LM317 ugh

[glops]

I have a couple of noise ensemble circuits in a box and added a separate perfed LM317 circuit at the 9v in to give me a regulated 9 volts as my onespot measures at
13 volts (!).  I use the AMZ calculator to help me find some resistors to get really close to 9 volts on my breadboard using the same power supply. The circuit was already boxed and the regulator circuit was added later.

I was testing the 317 on the breadboard just to get the 9 volt reading and was satisfied and perfed it up.  I then soldered a wire from the DC jack into the 317's in. Then, to the regulated out of the 317, I soldered my 9 volt wires for the leds and 9 volt circuit inputs. Once everything was soldered and mounted in the enclosure, my readings came in to around 6-7 volts, and the 7805 regulators dropped the voltage down to 4 volts instead of 5 volts.

Does anyone know why this is happening?  All I can think of is that there are 4 leds and two circuits and possibly some of the current is being lost. Any ideas?

[Jdansti]

The 1Spot should be regulated at 9v. Maybe something in it failed. R.G. should be able to help you with that.

I usually use a trimmer pot for the resistor, but my guess is that the 1Spot is not holding 13v at the input.  The LM317 requires the input to be at least 2.5v above the desired output voltage.  What do you measure on the input of the LM317 when you are seeing 6-7v at the output?

[a soBer Newt]

my onespot measures at
13 volts (!).

Is that with load or no load?

[glops]

The 1Spot should be regulated at 9v. Maybe something in it failed. R.G. should be able to help you with that.

I usually use a trimmer pot for the resistor, but my guess is that the 1Spot is not holding 13v at the input.  The LM317 requires the input to be at least 2.5v above the desired output voltage.  What do you measure on the input of the LM317 when you are seeing 6-7v at the output?

I was measuring ground and the output tab of the regulator.  Maybe the onespot is faulty.  I remember it used to run hot, terms of volts, but it seems that it has gotten hotter.

[glops]

my onespot measures at
13 volts (!).

Is that with load or no load?

Measures 13 volts when connected to a breadboard and when it's connected to a pedal...

[Jdansti]

13v at the LM317 input at the same time that you are getting 6-7v at the LM317 output?  If so, either the resistor is the wrong value or the regulator is not wired properly.

Double check the wiring per this:



Many people accidentally connect the output to the left pin (the adj pin as oriented above) instead of the center output pin.

[glops]

13v at the LM317 input at the same time that you are getting 6-7v at the LM317 output?  If so, either the resistor is the wrong value or the regulator is not wired properly.

Double check the wiring per this:



Many people accidentally connect the output to the left pin (the adj pin as oriented above) instead of the center output pin.

I double checked the pin out as I tested this on the breadboard first and then soldered everything up to my diagram. I guess I should desolder the 9 volt connections to my board and leds and remeasure.

It's really annoying as without the regulator I get a reading of 6.6-6.75 volts on the PT2399s and I just don't want them to fry.  My Max 1044 fried in my Gristleizer and it seems the cause of that would be the onespot.  I guess I could go buy another power supply and check that.

[R.G.]

Can you post a picture of the writing on the onespot?

A Visual Sound 1Spot puts out 9.4V nominal. If it's not that, then there is something wrong with it. Note that there were a few 12V 1Spots made for the pro audio market, but they were not many made and they have been discontinued. But even then, they were not 13V.

I personally like the LM317 very much. They're quite reliable and well behaved when applied properly.

[glops]

I'll post up a pic tomorrow.

[glops]

Here you go RG. Must be a damaged onespot as it measures at 13 volts now, sometimes 12.5 volts...

[R.G.]

Looks like the right stuff. I believe it must have failed in some way. Check your PMs.

It would be best not to use it on pedals in its current condition. Almost all of the faults that happen in that circuit result in it failing safe - at or near zero volts. Almost all. 

Till I get this sorted out, can you try your LM317 with something like a 9V battery or some such to get that part debugged?

[glops]

Looks like the right stuff. I believe it must have failed in some way. Check your PMs.

It would be best not to use it on pedals in its current condition. Almost all of the faults that happen in that circuit result in it failing safe - at or near zero volts. Almost all. 

Till I get this sorted out, can you try your LM317 with something like a 9V battery or some such to get that part debugged?

I replied to your PM twice, because my outbox says there's no messages. Let me know if you didn't get the reply.

I will try some batteries...

[R.G.]

I replied to your PM twice, because my outbox says there's no messages. Let me know if you didn't get the reply.

I will try some batteries...

I got both, have replied. The batteries will provide a way to separate questions about the circuit from questions about the DC supply.

[Paul Marossy]

A Visual Sound 1Spot puts out 9.4V nominal.

Whenever I use an LM317 voltage regulator, I set it to 9.5V. That's what my 9V batteries typically measure when they are brand new.

[Jdansti]

A Visual Sound 1Spot puts out 9.4V nominal.

Whenever I use an LM317 voltage regulator, I set it to 9.5V. That's what my 9V batteries typically measure when they are brand new.

If you're checking the whole circuit with the LM317 in place, it needs at least a few volts above the regulated voltage. You could probably hook up 2 9Vs in series to get 18V for your test.

[Paul Marossy]

A Visual Sound 1Spot puts out 9.4V nominal.

Whenever I use an LM317 voltage regulator, I set it to 9.5V. That's what my 9V batteries typically measure when they are brand new.

If you're checking the whole circuit with the LM317 in place, it needs at least a few volts above the regulated voltage. You could probably hook up 2 9Vs in series to get 18V for your test.

Not quite following you on that. I was just saying that when I use an LM317 (an adjustable voltage regulator), I set it for basically what a new 9V battery measures. Just thought it was interesting that the 1-spot is designed that way too. Anyway, if the LM317 is connected like it should be, as long as you've got a couple volts more than what you set it for, it shouldn't have to be messed with. If you set it to 9.5V, it should measure 9.5V no matter what you have connected to it (up to 1 amp IIRC).

[Jdansti]

A Visual Sound 1Spot puts out 9.4V nominal.

Whenever I use an LM317 voltage regulator, I set it to 9.5V. That's what my 9V batteries typically measure when they are brand new.

If you're checking the whole circuit with the LM317 in place, it needs at least a few volts above the regulated voltage. You could probably hook up 2 9Vs in series to get 18V for your test.

Not quite following you on that. I was just saying that when I use an LM317 (an adjustable voltage regulator), I set it for basically what a new 9V battery measures. Just thought it was interesting that the 1-spot is designed that way too. Anyway, if the LM317 is connected like it should be, as long as you've got a couple volts more than what you set it for, it shouldn't have to be messed with. If you set it to 9.5V, it should measure 9.5V no matter what you have connected to it (up to 1 amp IIRC).

Right-Sorry for the confusion and for telling you something you already knew.  I was thinking that you wanted to use an LM317 but you were having noise problems based on your first post:

I have a couple of noise ensemble circuits in a box and added a separate perfed LM317 circuit at the 9v in to give me a regulated 9 volts as my onespot measures at 13 volts (!).  I use the AMZ calculator to help me find some resistors to get really close to 9 volts on my breadboard using the same power supply. The circuit was already boxed and the regulator circuit was added later.

So my suggestion was to take your noisy circuit as you described above, and replace the 1Spot with batteries. I was just saying that if you did this, you'd need to use more than one 9V battery to get the input voltage high enough for the regulator give you ~9V out.

[Paul Marossy]

Right-Sorry for the confusion and for telling you something you already knew.  I was thinking that you wanted to use an LM317 but you were having noise problems based on your first post:

I have a couple of noise ensemble circuits in a box and added a separate perfed LM317 circuit at the 9v in to give me a regulated 9 volts as my onespot measures at 13 volts (!).  I use the AMZ calculator to help me find some resistors to get really close to 9 volts on my breadboard using the same power supply. The circuit was already boxed and the regulator circuit was added later.

So my suggestion was to take your noisy circuit as you described above, and replace the 1Spot with batteries. I was just saying that if you did this, you'd need to use more than one 9V battery to get the input voltage high enough for the regulator give you ~9V out.

Ha ha, that wasn't my post. I was just chiming in on the conversation with glops and y'all.  

For the record, I've never had noise problems with an LM317. I make sure it has a big filter cap on it and it's good to go.

[Jdansti]

Right-Sorry for the confusion and for telling you something you already knew.  I was thinking that you wanted to use an LM317 but you were having noise problems based on your first post:

I have a couple of noise ensemble circuits in a box and added a separate perfed LM317 circuit at the 9v in to give me a regulated 9 volts as my onespot measures at 13 volts (!).  I use the AMZ calculator to help me find some resistors to get really close to 9 volts on my breadboard using the same power supply. The circuit was already boxed and the regulator circuit was added later.

So my suggestion was to take your noisy circuit as you described above, and replace the 1Spot with batteries. I was just saying that if you did this, you'd need to use more than one 9V battery to get the input voltage high enough for the regulator give you ~9V out.

Ha ha, that wasn't my post. I was just chiming in on the conversation with glops and y'all.  

For the record, I've never had noise problems with an LM317. I make sure it has a big filter cap on it and it's good to go.

Oops!   Sorry about that Paul!  I thought that maybe Glops had forgotten his original problem!  As it was, I was the one who was mixed up.  Well, in my defense, I just turned 50 and now I've got an excuse for my mental lapses! (we need an old man emoticon!) (:~{)

[glops]

I haven't any time to do any debugging because of work but I'm sure I will be able to figure it out soon!