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DIY Stompboxes => Building your own stompbox => Topic started by: Cubes_Mahone on October 27, 2016, 11:22:45 AM

Title: IC based overdrive
Post by: Cubes_Mahone on October 27, 2016, 11:22:45 AM
Sorry for the noob question but:

I started on the IC Based od project by gaussmarkov http://www.diystompboxes.com/smfforum/index.php?board=33.0 (http://www.diystompboxes.com/smfforum/index.php?board=33.0)and I've stumbled on the first hurdle. I've following it exactly but my readings are coming out quite different.

http://diystompboxes.com/projects/power.html (http://diystompboxes.com/projects/power.html)
Around 2/3rds of the down where he shows using the multimeter to check voltages after putting the resistors in:
After the 100Ω resistor, his voltage drops from 9.46 to 9.44, mine drops from around 9 to 2.8

The voltage divider seems to be working as it drops to 1.4 there but his readings show 4.7 (around half of 9.44)

Any idea why this is? I've followed it exactly and I can't see any reason for this.

Thanks
Title: Re: IC based overdrive
Post by: Cubes_Mahone on October 27, 2016, 11:46:34 AM
Really sorry, ignore me. I put 22 ohm resistors instead of 22k ohm.

:-[
Title: Re: IC based overdrive
Post by: bloxstompboxes on October 27, 2016, 11:50:03 AM
Don't be embarrassed. It happens to the best of us. What rocks is that you found it yourself. You are on your way!
Title: Re: IC based overdrive
Post by: ashcat_lt on October 27, 2016, 12:46:28 PM
What rocks also is that the resistor didn't burn up.  Most of us build with 1/4W resistors at best, and 6.2V across 100R is closer to 3/8W. 
Title: Re: IC based overdrive
Post by: Cubes_Mahone on October 27, 2016, 04:28:57 PM
Quote from: ashcat_lt on October 27, 2016, 12:46:28 PM
What rocks also is that the resistor didn't burn up.  Most of us build with 1/4W resistors at best, and 6.2V across 100R is closer to 3/8W. 

It was pretty toasty when I touched it haha. I actually thought at first that it was a dud resistor so my first try was to change that resistor.

Ah well, it's taught me the importance of testing things as you go! We live and learn!
Title: Re: IC based overdrive
Post by: ashcat_lt on October 27, 2016, 07:53:09 PM
You might want to check that it is still within tolerance of 100R.  It could have been damaged even if not completely destroyed.
Title: Re: IC based overdrive
Post by: J0K3RX on October 27, 2016, 09:18:59 PM
A resistor is a few pennies... If they came close to turning into toast throw'em in the trash and save yourself a future headache.. :icon_wink:

I have put my thumb on a hot resistor quite a few times and it's always enlightening and sometimes even causes temporary Tourette Syndrome...  I just start blurting out swear words that I had no previous knowledge of and I may have even made up a couple new ones..

Actually, I put my thumb on a SCA-REAMIN hot resistor one time and it burned the perfect resistor shape into my skin. No kiddin :o For reals :icon_eek:
Title: Re: IC based overdrive
Post by: PRR on October 27, 2016, 10:27:37 PM
> I put my thumb on a SCA-REAMIN hot resistor one time and it burned the perfect resistor shape into my skin.

I had a picture of the image of a coke-bottle 6550 power tube burned into the back of my hand.