madbeanpedals::forum

Hi,

I have a roadrage hooked up to a dirtbag. On power up the sound is a little distorted and gradually that cleans up.

On power up the voltage from the roadrage to the dirtbag is 12.60 slowly going up to 14.00 volts max.
When not connected to the dirtbag the roadrage voltage reads 14.95volt.

The dirtbag draws 23ma and works fine from a regulated 15 volt power supply. It starts up right away and is not distorted on power up.

My conclusion is that the problem is in the roadrage. I replaced all capacitors. Orientation of caps is correct. Still the same result.
I am using LT1054, regulator is L7815CV diodes are as listed?

Where should i look now?

Thanks.

It could be an issue with the regulator. It sounds like it is not doing the job very well under load. If you have another one, you could try breadboarding the RR with a new regulator and see if you get better results powering the DB. That would tell you if it's the regulator causing the problem.

Hi brian,

I will try that. Have to get another regulator first.

Thanks, Marc

Ok, I breadboarded the roadrage.
Lt1054 and a lm317 ( with a 240r resistor and a 50k trimpot to bring it down to 15 volt). 2 1n5817 and a 1n4001. Caps as precribed. All new parts.
When I do not connect the dirtbag it stays fine at 15 volt. As soon as I connect the dirtbag the voltage drops and does not come higher then 11.20 volts.

The power supply I am using to power the roadrage is 9.60 volt, so a bit over the 9 volt but it can deliver 100 ma.

Two questions:
- should I now adjust the trimpot that determines the output voltage of the lm317 to 15 volt?
- as I wrote in a previous post my dirtbag draws 23 ma. It does that steadily and it works good on a 15 volt power supply. Could it be that 24 ma is maybe a bit too high for the LT 1054? How much do oher dirtbag builds draw?

Thanks, marc

Bump

In my experience, the LM317 does not perform too well when used with a charge pump once a load is applied to it. I've run into a similar problem with some sub-mini designs....it just does not regulate that well.

The problem with re-adjusting the trimmer is that it's possible it could spike at some point and then bye bye BBDs from too much voltage.

IOW, use what is recommended in the docs. A 15v T0-220 type regulator.
http://www.mouser.com/Power/Power-Management-ICs/_/N-6g7lv?Keyword=lm7815&FS=True

Hi brian,

Ok, that is clear. I will try to get another lm7815.

Thanks for thinking with me!

Ok, tried it again on the breadboard.
Regulator is 7815ct, this is what I can get here.
It delivers 15 volt but as soon as I connect the dirtbag voltage drop to 12,60 volts.

I tried it with other diodes in the road rage, 1n4001's instead of the 1n5817's. Slightly better at 13,59 volts wih the DB connected.

I have 18,60 volt just before the regulator so that should give the 3 volt difference the regulator needs to give 15 volt. With nothing connected i get 15,11 volt at the regulator.

Any suggestions?
Is this because I have to use a lm7815? Cannot find them here.
I really would like to get that steady 15 volt because the DB sounds better that way. I know because if
I use a 15 volt power supply it works fine.

What is the voltage that others have at their dirtbag?

Thanks

What's the current rating on you 18.6v supply?

If I measure the current at the input of the regulator it is 3ma without the dirtbag and a steady 28ma with the dirtbag connected.

I have build and rebuild it at the breadboard. Used different LT1054's, different diodes (1n4001's) and different 7815ct's . Still the same result.

I am stuck now.

I have a steady 15v on my roadrage plugged to my dirtbag.
I'm using Brian's board with a 7815 regulator i bought here:

http://www.musikding.de/product_info.php/info/p1094_7815CKC.html

Djaaz, did you measure 15 volt in the dirtbag and at the mn3005's? If you have a chance could you please measure how much current your dirtbag draws (after the roadrage).

Maybe i will have to get yet another regulator then.

Marc

Will do a bit later (two or three hours)
Sunday 7pm in France, dinner time and child story telling.

I thought i saw that you solved your issue?

No, not solved yet. Looked like that but it wasn't.

I suspect that the combination L1054 and regulator is rather critical.

Let me know what your measurements, voltage and current are.
Thanks.

Steady 15V. At the road rage, in the circuit everywhere.
My DMM refuse to give any intensity measure, don't know why but i will keep trying.

I had to find a 1 ohm resistor because my DMM would not take any mA measure and because i'm lazy.
I'm reading 21,5 mV which means 21,5 mA.

Hi Djaaz,

Thanks for doing that.
My built reads a little higher 23 ma, but that is maybe because of the bypass led I am using.
I will try to get that other regulator then.

Well, this keeps bugging me for a while now!! I can not seem to get this right.

I have build and rebuild the road rage, breadboarded it and ordered different regulators.
I ordered the same regulator Djaaz used and I still have the same problem.

The road rage give 14.88 volt and as soon as I connect the Dirtbag the voltage drops to 11.90 volts. This happens in every version I tried. I have tried this also with different wall power supplies (9volt 500ma)

My Dirtbag works fine and sounds good at a 15 volt power supply. No change in voltage when connected.
So now I start thinking that I have to start checking the Dirtbag.
These are the voltage readings of the Dirtbag when used with the 15 volt power supply:
IC1
1) 7.16
2) 7.23
3) 7.01
4) 0
5) 6,51
6) 7.23
7) 7.17
8 ) 14.79

IC2
1) 1.10
2) 1.79
3) 1.79
4) 0
5) 1.81
6) 1.78
7) 10.18
8 ) 1.80
9) 1.80
10) 7.88
11) 6.17
12) 1.81
13) 14.79
14) 1.79
15) 1.79
16) 0.17

IC3
1) 7.10
2) 7.11
3) 6.97
4) 0
5) 6,89
6) 7.11
7) 7.11
8 ) 14.79

IC4
1) 14.75
2) 7.41
3) 6.74
4) 6.74
5) 0
6) 7.41
7) 8.14
8 ) 0

IC5
1) 14.75
2) 7.41
3) 5.03
4) 5.02
5) 0
6) 7.41
7) 8.14
8 ) 0

IC6
1) 8.15
2) 8.14
3) 7.92
4) 0
5) 6.65
6) 6.82
7) 6.70
8 ) 14.80

IC8
1) 7.10
2) 7.10
3) 6.88
4) 0
5) 7.18
6) 7.90
7) 7.90
8 ) 14.79

What seems odd is the voltage at IC2 pin 16 and the voltages at IC5 pin3 and pin 4. Is this odd or not and what does it tell me?


Any suggestions?

Thanks, Marc

I swopped IC4 and IC5 and then the readings are changed with the IC. So there is something strange with IC5 with a low voltage at pin 3 and pin 4. Deffective chip? (That would be strange as the dirtbag is working and I have a good sound)

What creates the 0.17 volt at pin 16 of the IC 2?

bump?

Josh posted its voltage here:

http://www.madbeanpedals.com/forum/index.php?topic=3701.msg33203#msg33203

Quote from: gtr2 on February 01, 2012, 03:11:27 AM
Ok the charge pump was worth a try.  ;)  I was thinking maybe you were not getting enough mA for the circuit but you should have no problem with the LT1054.

Here are my voltages in an effort to help you and those in the future.  The input voltage is 14.75V.  I omitted IC7 since thats the modulation section.

Josh

IC1
1) 7.14
2) 7.14
3) 7.12
4) 0
5) 7.07
6) 7.14
7) 7.14
8 ) 14.74

IC2
1) 1.18
2) 1.78
3) 1.78
4) 0
5) 1.78
6) 1.78
7) 10.12
8 ) 1.78
9) 1.78
10) 7.73
11) 6.02
12) 1.78
13) 14.74
14) 1.78
15) 1.78
16) 0

IC3
1) 7.14
2) 7.14
3) 7.12
4) 0
5) 7.12
6) 7.14
7) 7.14
8 ) 14.74

IC4
1) 14.7
2) 7.29
3) 6.28
4) 6.27
5) 0
6) 7.29
7) 7.82
8 ) 0

IC5
1) 14.7
2) 7.29
3) 7.33
4) 7.33
5) 0
6) 7.29
7) 8.94
8 ) 0

IC6
1) 8.95
2) 8.83
3) 8.8
4) 0
5) 6.96
6) 6.98
7) 6.83
8 ) 14.74

IC8
1) 7.14
2) 7.14
3) 7.12
4) 0
5) 7.66
6) 7.73
7) 7.73
8 ) 14.74

I had a few mv on PIN16 as well when i troubleshooted my Dirtbag, my issue was not at all like yours and i solved it by changing the compander.

Hi!

I am having (yet another) problem with my Dirtbag.

It is working quite alright now with the v3205, but since I got MN3005´s and I´ve socketed all the critical values, I changed the IC´s.

I am using a nice 15V power supply, but I only get a loud hum and a tiny signal. If I use the 9V, then I get clean signal just ok (haven´t tweaked the trimpots to see if I can get any delay, but it would probably be just too distorted).

The power supply is working just ok with all my other effects, so I really have no idea what might have happened here. Does anyone?

Thanks!
André

I haven't built the Dirtbag yet. But from reading the build doc, there is more to the change between 3205s and 3005s than swapping ic's: jumpers, component values, etc.

Have you done all that?

SB

Yep, changed all the components, moved the traces next and below the IC´s, and removed the diodes and cap mentioned on the doc.

I was afraid I might have fried the MN3005´s, but I tested them on my DM-2 and they are ok. Funny thing is that on 9V it worked (clean signal at least). That´s odd...

Finally! Apparently it was something to do with the feedback pot.

Thank you very much Brian and everyone that helped me for giving me the oportunity to build such an incredible effect! I am absolutely amazed by the sound!

Back on the oiginal topic, if that is possible please.

I solved my problem.
The current the dirtbag draws (24 ma and slightly higher on startup) is on the edge of what the charge pump delivers. That is why it is dropping the voltage.
Apparently the combination of diodes, lt1054 and the 15 volt regulator ( i used a L7815CV) is more specific then I tought.
I breadboarded different combinations of different samples of the same part and noticed that this could make a difference of almost 1 to 2 volt!
Finally found the right combo that gives me a steady 14.95 volt with the dirtbag connected.
One to remember.

Thanks Djaaz for thinking wih me.
It is working fine now.
With 250k time pot (250k resistor parallel to that) instead of he 100k and a 270pf instead of the 250pf at the clock I have 560 ms of delay time.

Marc

Back on the oiginal topic, if that is possible please.

I solved my problem.
The current the dirtbag draws (24 ma and slightly higher on startup) is on the edge of what the charge pump delivers. That is why it is dropping the voltage.
Apparently the combination of diodes, lt1054 and the 15 volt regulator ( i used a L7815CV) is more specific then I tought.
I breadboarded different combinations of different samples of the same part and noticed that this could make a difference of almost 1 to 2 volt!
Finally found the right combo that gives me a steady 14.95 volt with the dirtbag connected.
One to remember.

Thanks Djaaz for thinking wih me.
I
It is working fine now.
With 250k time pot (250k resistor parallel to that) instead of he 100k and a 270pf instead of the 250pf at the clock I have 560 ms of delay time.

Marc

I had wondered if it was current draw (dropping voltage is a good sign of this), but figured that if it was, wiser heads than me would have said  :'(

Quote from: gitaar0 on May 05, 2012, 07:15:21 AM

Back on the oiginal topic, if that is possible please.

I solved my problem.
The current the dirtbag draws (24 ma and slightly higher on startup) is on the edge of what the charge pump delivers. That is why it is dropping the voltage.
Apparently the combination of diodes, lt1054 and the 15 volt regulator ( i used a L7815CV) is more specific then I tought.
I breadboarded different combinations of different samples of the same part and noticed that this could make a difference of almost 1 to 2 volt!
Finally found the right combo that gives me a steady 14.95 volt with the dirtbag connected.
One to remember.

Thanks Djaaz for thinking wih me.
I
It is working fine now.
With 250k time pot (250k resistor parallel to that) instead of he 100k and a 270pf instead of the 250pf at the clock I have 560 ms of delay time.

Marc

Hey Marc, just wondering what that final combination was?

I am getting different results every time I build a supply using the LT1054. The voltage drop of the 1n4001 seems to change results the most. I've also found for some reason LM7815 seems to work alot more consistently than 7815CV?

Andy

Andy

I am using LT1054, regulator is L7815CV diodes are 1n5817(2x) and a 1n4001.

Somehow I found that sometimes this combination works and sometimes it does not...probably a variety of the parts and the fact?
I still have no clue. My solution is that I breadboard the roadrage first and select the best suitable parts that way. It is strange as I have the impression that most others are not running into this problem.

Maybe it is the parts that I get here...who knows

Thanks, this isn't road rage specific but def LT1054 specific, I have 7815cv and 7915cv from Tayda and Futurlec which are MAR and CHN labelled at the bottom (country they're made maybe) and the ones from Futurlec (CHN) are working better... The ones from Tayda are reading all over the place on the diode test function on the mm.

The voltage drop of 1n4001's I have is all over the place too which is affecting input voltage to the regulators, not sure how this is affecting the output of the regs. Haven't tried 1n5817 yet, will try 1n60p.

Apparently the cap between pins 2 and 4 needs to be low ESL and ESR which can be achieved with a ceramic or tant in parallel. Same goes I think on the caps to ground at the voltage outputs.

This is quite pertinent, to me anyway.

http://brettcave.net/howto/circuits/PowerSupply_DualRail-LT1054-Straight.pdf
http://brettcave.net/howto/circuits/PowerSupply_DualRail-LT1054-Boosted.pdf

I am trying to draw upwards of 50mah though from the 1054, and have 2 of them paralleled, but the components seem to influence outcome more..

Andy