ProtoBoard Voltages Sanity Check

S

Spark_Trooper84

New member
I have just completed building the Protoboard.

Overall, the build was smooth enough, and i'm confident i do not have any solder bridges.
I socketed the TC1044SCPA IC, just to prevent the possibility of overheating the IC during soldering.
I sourced all the correct parts per the build documentation from Mouser and Tayda with no substitutions except the called for 100n (.1 uf) Film Capacitor.
I used a 100nf MLCC cap for that, but thats on the power circuit so i doubt that it's going to pose a problem.
If i'm wrong in that assumption, please correct me.

I'm using a D'Addario 9v power supply to power the board.

To test my work, I have powered the board and probed the head pins for voltages.
I'm getting some variations off of the specified voltages i expect to see from this probing, and want a sanity check.

The Multimeter I'm using is not the greatest, it's a cheap Commercial Electric branded unit I picked up from Home Depot.
With the probes shorted, the unit reads .03v

Setting the voltage probe to 20v, I get the following readings
3.3v header - 4.3v
REF header - 5.5v
5v header - 6.1--6.3v
9v header - 10.7-10.8v
-9v header - -10.0v
18v header - 20v

With these all measuring above the specified voltages, is this something i should be concerned with?
Is something wrong?

Thanks for any help.
 
Additional note.

I have the power supply plugged into the power strip of my computer.
I switched the plug in location on the strip and get the following voltages

3.3v - 3.93v
REF - 5.23v
5v - 5.94v
9v - 10.47v
-9v - -10.40
18v - 20.9v

And when plugged directly into a wall outlet on a separate circuit i get the same readings.

Just in case the information is relevant, here's the resistor/capacitor component tolerances and ratings used

MLCC .1uf (100nf) capacitor - 25V C0G 5%
47uf Al. Electrolytic Capacitor - 25V 20%
10uf Al. Electrolytic capacitor - 25V 20%
100uf Al. Electrolytic capacitor - 25V 20%
10k Resistor - 1/4W 0.1% Metal Film
 
Wondering if you installed the correct parts for your voltage regulators... Snap some pics that are clear so we can see your resistor bands and all the things..
 
So, here's a few images.

under power resistors, diodes, fuse & caps..
I'm aware that my soldering isn't pretty, but I know I have good bonds at least.
1000005547.jpg under IC socket and related caps/diodes 1000005548.jpg 1000005539.jpg 1000005540.jpg 1000005541.jpg 1000005542.jpg 1000005543.jpg i ordered this for the 5v, I followed the link in the build documentation.

1000005545.jpg i ordered this for the 3.3, I followed the link in the build documentation.

1000005546.jpg
 
swelchy said:
Wondering if you installed the correct parts for your voltage regulators... Snap some pics that are clear so we can see your resistor bands and all the things..
Click to expand...
I posted the same thing on the r/diypedals subreddit and got this reply:

"Since charge pumps aren’t voltage regulators and you have much of a load on the output of the charge pump, it’s normal to see higher voltages than what you ideally want. when you breadboard your circuits, you will see a voltage drop that will look closer to the ideal voltages you see on the pcb. if you want ideal voltages you must add some voltage regulators and more power filtering to get the least amount of noise possible."

Would this be the explanation, given that all components are correct (and assuming not malfunctioning/bad)?
 
When I get home later I'll probe my personal protoboard... From what I remember my voltages are a lot closer to values
 
Can you measure a known good 9V battery, by any chance?

All of your voltages are measuring high by a fairly uniform amount, that makes me suspicious of your meter.

Spark_Trooper84 said:
"Since charge pumps aren’t voltage regulators
Click to expand...

The LD33 and LD50 are voltage regulators and are both measuring high as well.

It's true that they are both unloaded, but your 9V supply isn't unloaded. It's powering two regulators and a charge pump, yet still measuring high.
 
Robert said:
Can you measure a known good 9V battery, by any chance?

All of your voltages are measuring high by a fairly uniform amount, that makes me suspicious of your meter.



The LD33 and LD50 are voltage regulators and are both measuring high as well.

It's true that they are both unloaded, but your 9V supply isn't unloaded. It's powering two regulators and a charge pump, yet still measuring high.
Click to expand...
Actually, I was already ahead of you, haha.

I don't have a 9v. battery handy, but i did just probe the power plug from the new power supply I have.

It measured on my meter at 10.92v

I probed a known good AA battery though, and got 1.837v rather than the expected 1.5...


So, seems likely the meter is reading +/- 20% high.
 
Last edited:
Well Team, Thanks for all of your valuable input.

I'm happy to report that the PedalPCB Protoboard does indeed work as advertised, and that my cheap old Multimeter was the root of my issue.

I purchased a new Klein MM325 and retested the board just now.
All voltages report back as being within .1 of a volt of their advertised values, with the one outlier of the 18v coming in at 17.78v on the meter.
So, well within tolerances, i believe.

Let this be a lesson to those who follow, cheap multimeters are cheap for a reason, spend just a little more and get a better one.
 
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