Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12, 2025) x

Thread Closed

40-140 Audio detector question
#5

More analysis theory. Hopefully this is easier to understand

After redrawing the circuit again. It looks like two functions are going on.
   
In my drawing I have the resistor #33e as 47k which is wrong it should have been #34 at 2.2meg.

On the diodes side of the transformer any positive voltage is shorted to ground which pushes all the negitive voltage to the detector side. This charges the caps 33C and 33D which act as filters but only at IF speed. There voltage discharges fast enough to follow the audio voltage.

While the caps 33C and D hold their charge and the IF changes polarity the voltage on the other side of the transformer sits on top of voltage of the caps which is now doubled and stored in C7 for use to control the gain of the IF stages.

Its interesting to note that both sides of the transformer are driving the two circuits negative which reinforce each other as voltage doublers.

All this still doesn't help me to figure out how this worked without the ground on the volume pot.

!!!!!!!!!!!!!!!!!!!RESISTANCE IS FUTILE!!!!!!!!!!!!!!!!!!!!!!  
                           /\/\/\/\/\/\/\/\/\
                                                     
                                 [Image: http://philcoradio.com/phorum/images/smi...on_eek.gif]  Chris


Messages In This Thread
40-140 Audio detector question - by OZ4 - 01-20-2019, 04:47 AM
RE: 40-140 Audio detector question - by radiodale - 01-20-2019, 05:49 PM
RE: 40-140 Audio detector question - by OZ4 - 01-20-2019, 06:19 PM
RE: 40-140 Audio detector question - by OZ4 - 01-20-2019, 09:57 PM
RE: 40-140 Audio detector question - by OZ4 - 01-20-2019, 11:58 PM
RE: 40-140 Audio detector question - by OZ4 - 01-21-2019, 06:10 PM
RE: 40-140 Audio detector question - by amptramp - 01-22-2019, 12:46 AM
RE: 40-140 Audio detector question - by OZ4 - 01-22-2019, 12:47 PM
RE: 40-140 Audio detector question - by amptramp - 01-22-2019, 08:35 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
54C Complete Teardown/Rebuild
Hello Roy, here is this one sincerely Richardradiorich — 12:45 AM
54C Complete Teardown/Rebuild
Richard, Had grabbed it already but thank you just the same.  I find myself wanting to find some way to block out the...glyphmon — 12:03 AM
54C Complete Teardown/Rebuild
Hello roy, here is a link to the schematic . Sincerely Richardradiorich — 11:54 PM
54C Complete Teardown/Rebuild
Richard, The Silvertone 2014 also is a transformerless set, so I am incorporating a 1:1 600 ohm audio isolation transfo...glyphmon — 11:37 PM
Preliminary work on wife's Silvertone 2014
Did an alignment today which was interesting.  IF alignment went great, almost all was already spot-on.  Adjusting on th...glyphmon — 11:35 PM
54C Complete Teardown/Rebuild
The main problem with adding a Bluetooth input is that this set lacks a traditional power transformer to isolate it from...radiorich — 11:19 PM
54C Cabinet Refinish
I started stripping this cabinet before it got super chilly out because I knew I wasn't going to be able to work on ...glyphmon — 11:18 PM
54C Complete Teardown/Rebuild
While I'm waiting to wrap up the final steps on my wife's Silvertone 2014, I started disassembly on the next project.  O...glyphmon — 11:07 PM
Preliminary work on wife's Silvertone 2014
Hello roy, that great news glad it worked out for you !! Sincerely Richardradiorich — 10:50 PM
Preliminary work on wife's Silvertone 2014
Safety caps arrived today.  Soldered one in and had a successful first power-up.  No magic smoke escaped and it tunes in...glyphmon — 09:53 PM

[-]
Who's Online
There are currently 1768 online users. [Complete List]
» 1 Member(s) | 1767 Guest(s)
Avatar

>