Road rage and dirtbag problem.

[gitaar0]

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.

[madbean]

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.

[gitaar0]

Hi brian,

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

Thanks, Marc

[gitaar0]

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

[gitaar0]

Bump

[madbean]

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

[gitaar0]

Hi brian,

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

Thanks for thinking with me!

[gitaar0]

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

[madbean]

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

[gitaar0]

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.

[djaaz]

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

[gitaar0]

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

[djaaz]

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?

[gitaar0]

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.

[djaaz]

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.