Well, I must commend Rod Elliott for his wonderful site and projects!
His P38 "auto relay" circuit works excellently for my BIC subwoofer. Yes, the sub has an "off-auto'on" switch, but since the power transformer in it is connected to AC at all times, it drew 50 watts AC no matter what. A few years back I installed a line on-off switch, but grew weary of having to turn the thing on every time I wanted to watch TV. (I use the sub to augment the tiny flatscreen TV speakers). Now, with a tiny transformer added for 12V to the P38 circuit, it now only draws 1, maybe 2 watts, until the P38 senses the sound from the TV, then kicks in the BIC transformer, then back off if no sound from the TV after 10 minutes. I'm happy.......
His other project, P99, a Sallen-Key steep rumble filter, is great for the console stereo I re-designed, as well as a custom jukebox I designed. No more "feedback" and howling at high volumes when playing records, and who needs "sub-sonic" crap in their music anyway?
The man is a genious. Much thanks Rob, if you read this. Keep up your fine work. 🙂
His P38 "auto relay" circuit works excellently for my BIC subwoofer. Yes, the sub has an "off-auto'on" switch, but since the power transformer in it is connected to AC at all times, it drew 50 watts AC no matter what. A few years back I installed a line on-off switch, but grew weary of having to turn the thing on every time I wanted to watch TV. (I use the sub to augment the tiny flatscreen TV speakers). Now, with a tiny transformer added for 12V to the P38 circuit, it now only draws 1, maybe 2 watts, until the P38 senses the sound from the TV, then kicks in the BIC transformer, then back off if no sound from the TV after 10 minutes. I'm happy.......
His other project, P99, a Sallen-Key steep rumble filter, is great for the console stereo I re-designed, as well as a custom jukebox I designed. No more "feedback" and howling at high volumes when playing records, and who needs "sub-sonic" crap in their music anyway?
The man is a genious. Much thanks Rob, if you read this. Keep up your fine work. 🙂
Better Quality PCB's Please
Rod Elliott has good stuff to read.
Rod if you are reading I would be willing to pay more and buy more of your PCB's if they were better quality.
Finding shorted traces when I turn thing on is no fun.
Thanks DT
Rod Elliott has good stuff to read.
Rod if you are reading I would be willing to pay more and buy more of your PCB's if they were better quality.
Finding shorted traces when I turn thing on is no fun.
Thanks DT
That's why it pays to inspect boards first, for any possible minute flaws.
It's common sense, and part of careful assembly.
Hello,
The boards that I have purchased from Rod have been consistently Bad, the worst.
I am willing to pay more to get better.
Give them a look see, sure.
Quality Control is not my job.
Thanks DT
At least you got the boards.
Two months later and I have nothing and all I got when I emailed is "I mailed them, my work is done"
The first amp I built was Rod's P101 back in 2004. It still plays beautifully. The boards I got from him looked home etched but worked fine. I would think with the cheap prices from board houses today he would have his boards made nowadays.
Rod site is great.
There is a lot to learn, check and fully understand.
Better than books about DIYing audio.
Good at debunking audio myths.
A best resource.
There is a lot to learn, check and fully understand.
Better than books about DIYing audio.
Good at debunking audio myths.
A best resource.
Unfortunately there are no PCBs for project 38 "Signal Detecting Auto Power-On Unit" available on his site. Does anybody have gerber files for this project or something equivalent and is willing to share them?
Many thanks
Many thanks
I bought these boards and have them on the bench but not installed yet - they seem to work very well.
Some things that are important to know:
It is the smallest and most convenient board (as it has its own power supply) with this funtionality that I could find. If you tend to fall asleep with your class A amps running all night, this might help a bit with your electricity bill.
Some things that are important to know:
- size is 57x77 mm²
- max sensitivity is around 20mV ( adjustable with the 20k trimpot)
- by default the board always switches power on, when first powered up regardless of the presence of an audio signal
- the turn off delay is determined by a resistor. In my case it was a 1.8MOhm where the silk screen shows a 1M trimpot. This gives around 3 minutes. I replaced with a 4.7MOhm which gives around 15 minutes delay when first powered on and 8 minutes during operation.
It is the smallest and most convenient board (as it has its own power supply) with this funtionality that I could find. If you tend to fall asleep with your class A amps running all night, this might help a bit with your electricity bill.
Attachments
I built Project 38 several times for subwoofer duty, on perf board.
It works great.