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voltage regulator wiring

Started by jdub, March 14, 2011, 10:37:49 AM

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jdub

March 14, 2011, 10:37:49 AM
Greetings  :)
Did a search for this but didn't find exactly what I'm looking for.  I'm currently working on a project- MXR flanger clone- that requires 15vdc, and this is new territory for me since my numerous other projects have all been 9v.  So, I attempted using a MAX1044 charge pump (from GEO) to supply ~17.5v to a 78L15 regulator, on a little daughterboard; this setup yielded ~14.85v unloaded, but when when the circuit was connected the voltage at the output of the 78L15 dropped dramatically (~6v) and I noticed a burning smell from the daughterboard.  Now, I am assuming (perhaps incorrectly) that is signifies insufficient current being supplied to the circuit: the 78L15 can supply ~100mA (which should be sufficient for this circuit), but I am uncertain as to the current output of the MAX1044 pump (I've read varying reports).  The other possibility is that I simply wired the daughterboard wrong.  Since my next step will be to try a different daughterboard using an LM317 regulator (1A capability) powered by an 18v-24vdc wallwart, I just want to be certain that my wiring is correct.  Would the proper wiring, then, from the DC jack be: DC jack gnd lug to both input jack sleeve and daughterboard gnd, jack + lug to LM317 input, 317 output to circuit board + input and circuit gnd to daughterboard gnd? Does this sound correct?  For some reason I can't seem to visualize this confidently, so any advice would be appreciated.  BTW, the daughterboard circuit is the standard adj circuit as found on the LM317 datasheet and the circuit has a 220uF cap (25v) at the power supply input.

Thanks!
A boy has never wept nor dashed a thousand kim

Govmnt_Lacky

#1
March 14, 2011, 11:06:32 AM
I am also in the middle of cloning the M-117  ;D

This is exactly what I am trying to do in order to supply the +15VDC. I have both the TO-92 AND TO-220 version of the 7815 regulator.

My plan was to "borrow" the design from the GGG PT-80 layout. On that layout, they run the voltage from the charge pump circuit into a 12V and 5V regulator (both are TO-92 series regulators)

I was just about to post the following questions:

1) What is the voltage input to the 78L12 and 78L05 regulators on the GGG PT-80 circuit?
2) What is the current draw on the MXR M-117 Flanger?

I have read elsewhere that the current draw on the M-117 is around 45-60mA but I would like a definite answer on that. I may just go with the TO-220 regulator (handles up to 1A)

If memory serves me correctly, the output from the PT-80 charge pump is about 17V but I also want confirmation on this too.

I will be keeping an eye on this thread. What a coincidance  :D
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

jdub

#2
March 14, 2011, 11:32:19 AM
Good timing, indeed!  :D

Yeah, I didn't have a 7815 (which I believe is 1A), only the 78L15, which is only 100mA.  Still, I would think that would be sufficient (I also figured 45-60mA draw for the m117), which leads me to think that the MAX1044 charge pump just doesn't put out enough current- and I assume that if the pump is insufficient, the regulator it feeds will also be insufficient...right?  I'll have to check out the PT-80 circuit...
Still curious about the wiring of my daughterboard, though...any thoughts on that? ???
A boy has never wept nor dashed a thousand kim

Govmnt_Lacky

#3
March 14, 2011, 11:37:15 AM
Quote from: jdub on March 14, 2011, 11:32:19 AM
Still curious about the wiring of my daughterboard, though...any thoughts on that? ???

I was going to do this but, you may be able to get to it first.

Try "reproducing" the PT-80 pump circuit on breadboard. It should only require the 1044, three 4148 diodes, two 10uF electro caps, and one 100uF electro cap. Then, insert your regulator and see if you are getting the right voltage.

Next, wire it (temporarily) to your M-117 circuit. See if that flies  ;)
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

thedefog

#4
March 14, 2011, 12:06:50 PM
Is it that much of a pain to just use a dedicated 18v adapter and skip the 1044 all together?

jdub

#5
March 14, 2011, 12:15:18 PM
Good point...I just figured I'd try the pump circuit for convenience, cuz I have the parts and extra 9v adapters.  I have no problem getting a dedicated adapter for it at the thrift store or something, I just don't have one right now.
A boy has never wept nor dashed a thousand kim

Govmnt_Lacky

#6
March 14, 2011, 12:27:40 PM
Quote from: thedefog on March 14, 2011, 12:06:50 PM
Is it that much of a pain to just use a dedicated 18v adapter and skip the 1044 all together?

Quote from: jdub on March 14, 2011, 12:15:18 PM
I have no problem getting a dedicated adapter for it at the thrift store or something

You need to work with the 15V regulator anyway, how much more hassle is it to use the charge pump? The chip is probably less than the cost of a wall wart and the design is already done (if the PT-80 circuit is workable)

Maybe a little more work but the ability to use a 9V battery AND a 9V power supply is appealing to me. If you just go with the regulator, you will NOT HAVE THE BATTERY BACKUP.

I guess its up to the individual  :D
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

jdub

#7
March 14, 2011, 12:57:38 PM
Also good points...I just wanna get the thing working  ;D.  But in reference to this situation, IS the MAX1044 charge pump even capable of providing enough current for the M117 circuit? What about the LT1054? I was reading the PT80 notes, and apparently the draw from that circuit is only around 25mA, and I'm not really certain how accurate the figure for the M117 is (if it's the figure from the posts at Shredaholic, it refers to the draw from the reissue M117).  I'm not sure how to calculate the current output of the 1044 pump circuit in this instance. 
A boy has never wept nor dashed a thousand kim

Govmnt_Lacky

#8
March 14, 2011, 01:36:38 PM
I will look into the LT1054.

I researched the MAX1044 and unfortunately, it looks like the MAX current draw for that chip at 9VDC is around 40mA  :'(

So.... it looks like it won't cut the mustard.

I will post back when I find out about the LT1054
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

jdub

#9
March 14, 2011, 01:55:06 PM
Thanks, man.  Will do likewise.
A boy has never wept nor dashed a thousand kim

Govmnt_Lacky

#10
March 14, 2011, 02:54:54 PM
Looks like the LT1054CP will handle up to 100mA over the FULL supply voltage range which is 3.5V to 15VDC  ;D

This is all preliminary and I want to confirm with TI tech support before conforming but it looks promising.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

jdub

#11
March 14, 2011, 03:04:49 PM
OK, according to the LT1054 datasheet, the chip has a max output current of 100mA; however, the datasheet shows a voltage doubler circuit with a stated output current of 50mA.  Stands to reason, since by Ohm's if you double voltage you halve current. Talked about in this thread: http://www.diystompboxes.com/smfforum/index.php?topic=66084.0 and here: http://www.diystompboxes.com/smfforum/index.php?topic=60871.0.  50mA seems marginal for this circuit... I'm thinking wall wart at this point...  :-\
A boy has never wept nor dashed a thousand kim

Govmnt_Lacky

#12
March 14, 2011, 03:31:30 PM
I wonder if there are ANY voltage doublers that can handle over 50mA draw at 9VDC input  ???
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

jdub

#13
March 14, 2011, 03:56:10 PM
I did see mention in one thread about doublers based on 555 timers being capable of handling 70-100mA, but apparently current spiking is a problem & I wonder about noise in audio applications... if you google 555 voltage doubler there are some circuits to check out.  There are also some threads here.
A boy has never wept nor dashed a thousand kim

Govmnt_Lacky

#14
March 14, 2011, 03:58:43 PM
I am not familiar with implementing voltage regulators in designs. I usually build them with the regulators already incorporated. I started a new thread here:

http://www.diystompboxes.com/smfforum/index.php?topic=90457.msg768879;topicseen#msg768879

Basically, I am asking for help on just implementing the regulator and whether or not it needs additional filtering.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

jdub

#15
March 14, 2011, 04:30:56 PM
I've never used one either.  My basic points here were to find out if overdraw of current was my problem with the MAX1044 circuit (which I'm pretty sure it was) and to make sure I was wiring the thing correctly.  Still not sure about that!  :D
A boy has never wept nor dashed a thousand kim

Govmnt_Lacky

#16
March 15, 2011, 11:32:11 AM
After some email banter back-and-forth with TI, I was sent this about the LT1054CP voltage doubler circuit:

"I just confirmed with specification team. The maximum  output current of 100mA also applies to VIN=9V. Let me know if you have further specfic questions or feedback..

Naser Salameh
Texas Instruments
Semiconductor Technical Support"

I am going to get some more confirmation about this but it appears that it will handle the 50-75mA draw of the M-117 Flanger circuit. Unlike the MAX1044.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

jdub

#17
March 15, 2011, 01:56:55 PM
Nice  ;D  Definitely worth a shot- I have a couple of Linear LT1054s to experiment with.  I think they're pin compatible with the MAX1044 except they don't need to connect pins 1 & 8 for high frequency, correct?

BTW, thanks for your help with this, G.L.!
A boy has never wept nor dashed a thousand kim

Govmnt_Lacky

#18
March 15, 2011, 02:11:26 PM
Quote from: jdub on March 15, 2011, 01:56:55 PM
Nice  ;D  Definitely worth a shot- I have a couple of Linear LT1054s to experiment with.  I think they're pin compatible with the MAX1044 except they don't need to connect pins 1 & 8 for high frequency, correct?

BTW, thanks for your help with this, G.L.!

I would DEFINITELY breadboard the Doubler and test. Implement a polarity protection diode AFTER the 15V regulator as well.

Let me know what you come up with when you breadboard it.  ;D
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

jdub

#19
March 15, 2011, 02:41:12 PM
Dig it.   Working evenings, though, so it might be a day or two.
A boy has never wept nor dashed a thousand kim
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