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Old May 18, 2004, 07:19 PM
Registered User
Joined Jun 2003
17 Posts
Voltage Regulator question

This may be a stupid question, but here goes:

I have 4 Duralite 5.1Volt Voltage regulators. I have been using 5 cell NiCD packs for helicopter receivers. I noticed the sound of one of the Futaba 9252 servoes sounded a little different one day, so I thought I'd check the voltage coming through to the receiver. This is what I found:

Batt Voltage 7.03

Reg#1 output - 6.03
Reg#2 output - 5.96
Reg#3 output - 5.79
Their age ranges from a year and a half to 3 months old.

I called Duralite...who were very kind and helpful(no flack please, I'm NOT slamming Duralite, I am VERY happy with their service!)...who told me to send them in for inspection and adjustment.
I did so, and ordered another one to use in the meantime.
Duralite sent me 3 NEW regulators in return! (ah...good customer service is such a rare commodity these days!) Out of curriosity, I tested all 4 and found the following:

Batt Voltage 6.52

Reg#1 output - 5.78
Reg#2 output - 5.78
Reg#3 output - 5.78
(Note: 1, 2 & 3 were sent as the replacements, 4 was received prior to their arrival).
Reg#4 output - 5.65

My questions are:
1. Is it neccessary to measure the voltage with a load (and if so how, and how much?)
2. Why do you think all 3 received at the same time have identical output, while the other one varies?
3. What would be normal tollerances for this type of regulator?

Once again, please don't take this as an unhappy Duralite customer...on the contrary, I have received better service than just about anyone else in this industry...I just don't know what type of results to expect.

Thanks for your time!
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Old May 23, 2004, 01:49 PM
Registered User
Joined Jun 2003
17 Posts
Hey Guys...Found the answer!

Found the answer on RunRyder .
Raptor Rulezzz hit the nail on the head. I measured the battery pack at 6.49 Volts. Then hooked up two servos to a receiver and put a servo extension lead in one channel to allow me to measure the voltage.

With everything turned on I measured:

5.18 volts through regulators 1, 2, & 3
4.98 volts through the fourth regulator that was received later.

Obviously it must be under a load before it starts to regulate the voltage, and as Mr. Cole stated his estimate as 1 - 2% on the regulator chip tollerace, it looks like they are pretty close.

Thanks again for everyones help...I will sleep better tonight.
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