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MP3 player with old radio : one solution .

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Topic: MP3 player with old radio : one solution .
Posted By: nali
Subject: MP3 player with old radio : one solution .
Date Posted: Jan/29/2010 at 9:08pm
Here s the goal ..
Using a modern mp3 player on a vintage radio without paying 100 $ .
We can for 5 $ , in fact 2  $ if you get a free box for this , a soldering iron and a few wires . Notice the commercial
adaptor also need soldering , if they are not FM transmitters . What if you just have mono AM ? :P
If you have to fix something , you d better know how it works ...
So a few basics : It s really basic knowledge , easy to understand for people not familar with electronics , so be indulgents if I explain it quite easily ...

Any car radio , home amplifier or whatever basicelly works the same way . You need a source , to provide a low signal  from CD player , radio, 8 track tape or whatever .
Then , you need a power stage , to move the loudspeakers  . It s the amplifier .
Mostly all radios have  an ampli inside . Not always really powerfull , but there s an amplifier . Usually between 4 or 11 watt in an old stock radio .

Between the source and the amplifier , there s a way to choose how much output ( sound  ) you want from the radio . It s the volume button .

This is were we can play ....

A volume button works quite like a rheostat , the same we have to have more or less light in the dash .
The source comes from the top , and bellow is the ground . The middle cursor move between both and is connected to the amplifier .
The shape is just round :P
So if you turn left , you move the cursor to the ground , less sound , if you turn right , you go to full source and have more sound .
Just as easy ....
http://www.servimg.com/image_preview.php?i=323&u=12474091">



So  ... What now ?  Instead of sending to the amplifier the sound comng from the radio, we can send the sound from
anything .  
The ugly way would be to cut the wires coming from the source , and solder wires connected to a mp3 player .
For just 2 $ more , we ll give the beast 2 lifes .

Remember the FM receiver you had . Usually the sound comes from the loudspeakers , but when we plug ears , the speakers
stop and there s sound only in the ears .
It s just a mecanical connector . That s what we have to use .

Go to any electronics store parts , and ask for a stereo jack connector ( 1/8 I think ), with a mecanical switch , to  choose from head / speakers .
Cut wire on the volume button , inside the radio ,
Test it with your favorite Beckman , Fluke , ohmetre , solder it so that without anything plugged inside the sound comes from the radio , and when you plug a mp3 player , the sound comes from it . It s stupid and easy but it s enough .
In french , but quite easy to understand :
http://www.servimg.com/image_preview.php?i=324&u=12474091">

Oh .... Your mp3 player is stereo and your radio is mono ....  Connect the right and left throught 120 ohms resistors ,
that s all  ( 80 to 220 ohm in fact , to be safe ) .

PRO :
easy.
cheap.
it works .

CONS :
You have to solder inside the radio, this may kill it .

The ground from your volume button may not be the same ground as the radio ground . I STRONGLY recommend not to plug a
USB mp3 player to a USB charger in the lighter , unless you are SURE the ground is the same .
In my Ambassador , it s not the same ground . This could results to dead for the radio, electric fire , or ugly noise
in the loudspeakers .


More : you can plug 2 RCA output after the cursor and add an external amplifier , so you can enjoy classic music on
mono AM with 500 Watt :P

I know it s quite simple , it works for me , but take care to what you do . I m not responsible for anything if you
kill your cat , neighboor , wife , etc ..
I m french , so my english may not be perfect  . If anyone wants to correct me , I ll be glad of it .
Phil






Replies:
Posted By: danahyatt
Date Posted: Dec/13/2010 at 10:36pm
This seems too simple, and most certainly one will have a voltage at the rheostat post you described (Noted: you do use a resistor).  The voltage at the rheostat post will damage the MP3. My understanding is to use the amplifier; one will need to connect where the tuner input is to the amplifier. Yet disconnect the tuner signal wave from the input to the amplifier. By inputting the MP3 signal to the amplifier one will have a full amplified signal strength to the speakers.  I don't read or write French but I do read schematics and these drawings are probably useless to many people who read this blog.


Posted By: danahyatt
Date Posted: Dec/13/2010 at 10:39pm
Additionally, I do have vintage cars but would like to keep them original so I will not mess with my radio to install an MP3.


Posted By: gryzynx
Date Posted: Dec/14/2010 at 12:46am
Well, that looks easy enough and is fundamentally sound, but you need to be careful. I actually have done this many years ago.
 
I hope everyone gets the point that your AM radio is mono, (1 channel) and you mp3 source is stereo, (2 channels). It will work, but you won't get the sound quality you may expect. The trick with the resistors will get the L+R signal to the single, mono input, but it will not give you a stereo output.
 
One thing that may be lost here is the fact that your volume control shaft actually serves 3 functions, power on/off, volume and tone. The three connections Nali refers to need to be for the volume control only. If you refer to the picture, you may see that the control is divided into 3 sections. The rear portion has two wires and  controls power. +12 V is switched on and off here when you turn the volume control. The front section uses 3 wires and performs the tone control function. The middle section is the volume control. The view you see is with the bottom plate of the radio removed. The middle section, (volume control), has 3 connections. The middle connection is the one Nali refers to as the cursor. The english name would be the wiper. The signal source and ground are exactly as described and can also be called the hi, (source) and lo,(ground) connections to the volume control. You need to determine the difference between these two connections and the easy way is to look at the volume shaft straight on and envision the arc travelled by the movable contact, (cursor, or wiper),as you increase/decrease the volume. If the connections are at the bottom of the control, (as I suspect they are in this example), the cursor will travel from the left terminal, (lo or ground) at minimum volume to the right terminal, (hi or source) at maximum volume. This would place the ground terminal closest to the outer frame, (white wire) and the source at the terminal towards the inside of the chassis, (white/black stripe).
 
The next thing you have to organize is the jack you purchased. This will be similar to the earphone plug already on your mp3 player. These plugs make 3 connections. They are called tip, ring and sleeve. If you examine the plug, you will easily identify which ones they are. The ground, or signal low is common to both left and right sources. It is formed by the sleeve, (circular contact band nearest the wire end of the plug). The tip and ring, (tip and middle band) make the L and R source connections. You may need our continuity checker, or ohmmeter to identify these connections on your jack.
 
The example Nali provides contains two extra connections called normalling connections. These are used to connect the radio source to the volume control when the plug is removed from the jack. Using your continuity checker, identify which plug connection mates with the jack connection when the plug is inserted. These are identified as sortie droite, (left source), sortie gauche, (right source), and masse, (ground) on the diagram. (Pardon my French Nali). The resistors mentioned to connect both sources to the mono input at the volume control will be connected in a Y configuration with one lead each channel towards the jack and one lead, (two resistors) to the source side of the volume control. It may be advisable to add a capacitor of about 0.05 microfarads between the jack and the volume control to provide DC blocking. between the mp3 player and the radio. 
 
The radio source, (white/black stripe) that was removed from the volume control should be connected to the normalling contacts of the jack to enable normal function of the radio when the mp3 source plug is removed. You can identify the normalling contacts with your continuity checker when the plug is removed from the jack. First, they are the two that are left over and one will connect with the tip and the other with the ring when the plug is removed. They will disconnect and isolate when the plug is inserted to the jack.
 
Still heed the warning about using the USB adapters to power the mp3 player as they may float the ground and the ground thru the radio via the masse/signal lo is really chassis ground and you could develop unwanted current of a significant magnitude.
 
One last consideration should be the nature of the input you have just provided. It is a low level input and you need to take care to not overdrive this input. The volume on you mp3 or other device should be set to a point where you cannot drive your speaker to distortion with the radio volume control. If you mp3 source is set too loud, the sound will be distorted at almost any setting of the radio volume control.


Posted By: ronilevi
Date Posted: Dec/29/2010 at 3:05pm
Hi all!

I would really love to try out this hack on my '66 Ford radio but I am having a little trouble locating the stereo jack with the internal switch. From what I could find, the local Radioshack does not carry these so I have to resort to online retailers and I want to be certain that my purchase will work.

If I understand how this works correctly, the jack is normally shorted when there are no headphones (or mp3 player) connected to allow the signal from your antenna to stream through. When you plug in your mp3 player the connection cuts the antenna signal and instead feeds from your plugged in device. From what I understand, this is accomplished through the use of an electrical shunt and that is what I should be looking for in the jack that I purchase.

If what I stated is correct, then http://www.allelectronics.com/make-a-store/item/SMJ-6/3.5MM-STEREO-MINI-PHONE-JACK-W/2-NC-SHUNTS/1.html - this device should work right? If you have better suggestions or if I am mistaken in any way, please let me know.

Also in response to gryzynx:  using a 0.05 uF cap between the mp3 source and the volume control is a great idea! I have two questions about this:
1) Will this have any negative effects on the sound by filtering frequencies?
2) If it blocks the DC then wouldn't this negate the potential problems of charging the mp3 device while it is playing through the radio (due to the fact that the grounding *may* not be the same)?


Posted By: sidewinder
Date Posted: Dec/29/2010 at 3:16pm
Just found this site recently...they will do an MP3 for your radio for under $100.00, also they restore vintage radios.....  Good to know....

http://www.wardsclassiccarradiorepair.com/index.html - http://www.wardsclassiccarradiorepair.com/index.html

Chuck Page


-------------
Chuck Page ,AKA Sidewinder
1968 "BLACK CHERRY" Javelin
Previous owner of 2013 Heritage Cup winner 1970 BBO AMX




Posted By: crazy4amc
Date Posted: Dec/29/2010 at 5:52pm
I;m an audio tech by trade however I don;t work on internals of old car stereos but I can tell you that ingeneral you have two types of pre-amplifier signals ( mic level, line level), you have to be very careful to not put a line level into a device that is looking a mic level because it can overdrive the amp circuit and blow up speakers and amps. Also you match the levels by using a transformer not resistors since audio signals are ac not dc and require step down through a transformer, direct boxes do this for you using switchable transformers.

-------------
Crazy4amc


Posted By: gryzynx
Date Posted: Dec/29/2010 at 7:35pm
Originally posted by ronilevi ronilevi wrote:

.

If what I stated is correct, then http://www.allelectronics.com/make-a-store/item/SMJ-6/3.5MM-STEREO-MINI-PHONE-JACK-W/2-NC-SHUNTS/1.html - this device should work right? If you have better suggestions or if I am mistaken in any way, please let me know.

Also in response to gryzynx:  using a 0.05 uF cap between the mp3 source and the volume control is a great idea! I have two questions about this:
1) Will this have any negative effects on the sound by filtering frequencies?
2) If it blocks the DC then wouldn't this negate the potential problems of charging the mp3 device while it is playing through the radio (due to the fact that the grounding *may* not be the same)?
For the jack you sourced, yes, it will work.
 
Q # 1, this is a somewhat complicated issue. The value of the capacitor, in conjunction with the impedence of the input will affect low frequency response. Given the values expected in the radio volume control circuit, this should not be noticeable with 0.05 uF.
Q # 2, the capacitor will not change anything as far as grounding. The capacitor would only be on the "hot" side of the circuit and the danger is in different ground potentials. There could be an alternative in using a transformer as suggested, but that changes the design of Nali's original circuit. Transformers would have to be chosen carefully for impedence and ratio and would add considerable cost to the mod.
 


Posted By: gryzynx
Date Posted: Dec/29/2010 at 7:49pm
Originally posted by crazy4amc crazy4amc wrote:

I;m an audio tech by trade however I don;t work on internals of old car stereos but I can tell you that ingeneral you have two types of pre-amplifier signals ( mic level, line level), you have to be very careful to not put a line level into a device that is looking a mic level because it can overdrive the amp circuit and blow up speakers and amps. Also you match the levels by using a transformer not resistors since audio signals are ac not dc and require step down through a transformer, direct boxes do this for you using switchable transformers.
 
The point described in the original post is typically in the -10 to -20 db(mv) range. They also are likely around 10K impedence. As you probably know, line levels are typically 0 dbm @ 600 ohm impedence. Point well taken about overdriving the input, but the resulting distortion would likely have you turning it off well before any speaker and/or amp damage is done given the typical car audio specs of the OEM radio. For everyone else, please forgive the techno mumbo jumbo.
 
I think you are missing the point about the purpose of those resistors. They are not to "match levels", rather, they are being used to sum the two low impedence outputs of the L and R audio source from the MP3 player into a single mono analogue signal while providing adequate isolation between the two outputs. The value chosen is probably a good compromise between isolation and minimal signal loss. Remember, this is offered up as a $5 fix. Sky is the limit if you want to reengineer the whole works.


Posted By: RSX 401
Date Posted: Dec/29/2010 at 10:36pm
Has anyone considered something like this?
 
http://www.rediscoveradio.com/ - http://www.rediscoveradio.com/


-------------
I'll follow these lines a little ways more,

Until I can find what I'm looking for.

With the pedal to the metal,

I'm gaining my speed.

Riding down low in my AMC.....


Posted By: sidewinder
Date Posted: Dec/30/2010 at 8:30am
The problem with all of this is that you still end up with a plain old mono sound system.  I'm planning to get my radio rebuilt to a stereo unit.... Has anyone used these guys??

http://www.turnswitch.com/ - http://www.turnswitch.com/

Chuck Page


-------------
Chuck Page ,AKA Sidewinder
1968 "BLACK CHERRY" Javelin
Previous owner of 2013 Heritage Cup winner 1970 BBO AMX




Posted By: ronilevi
Date Posted: Dec/30/2010 at 5:44pm
@ Sidewinder:
The beauty of this is that it is dirt simple and does not require much more than the mini RCA jack.

Gryzynx stated:
Originally posted by gryzynx gryzynx wrote:

 
I think you are missing the point about the purpose of those resistors. They are not to "match levels", rather, they are being used to sum the two low impedence outputs of the L and R audio source from the MP3 player into a single mono analogue signal while providing adequate isolation between the two outputs. The value chosen is probably a good compromise between isolation and minimal signal loss. Remember, this is offered up as a $5 fix. Sky is the limit if you want to reengineer the whole works.


What this equates to is no loss of signal by playing a stereo source (your mp3 player) through your mono radio.

@ Gryzynx:

Thanks for answering my questions. I am going to purchase this jack straightaway!

As far as your response on the capacitor, I will have to further investigate this DC blocking you referred to and maybe reevaluate my understanding of it.

I am going to proceed with this hack as soon as my part comes in. I'll try and repost here on my progress and findings.


Posted By: Mean71
Date Posted: Jan/01/2011 at 10:47am
Why not just buy a super cheap stereo from ebay or Amazon for $50 and install it in a hidden place?  That's what I plan on doing with my Javelin.


Posted By: sidewinder
Date Posted: Jan/01/2011 at 10:59am
dan....1)  where the heck can you hide it?   2)  more wires and crap    3)  if it's hidden don't ya think it will be hard to change stations etc....   to each his own but I'm having my radio converted....

Chuck Page


-------------
Chuck Page ,AKA Sidewinder
1968 "BLACK CHERRY" Javelin
Previous owner of 2013 Heritage Cup winner 1970 BBO AMX




Posted By: gryzynx
Date Posted: Jan/01/2011 at 7:20pm
I think the beauty of this is that you can grab the volume control of the stock radio in the stock location and crank up some audio media that you may actually want to hear. Last time that happened to me was in 2008 when I picked up my Rambler fresh from it's engine rebuild in Oakbank, Manitoba and turned on 1290 CFRW which was playing an all oldies format at the time. (They have since changed to an all sports format and I no longer live in the area.) Stock radio remains functional and original. Broadcasting has lost it's luster over the years and programming selection may be spotty depending on your locale. Of course, sound quality is not up to even the most inexpensive aftermarket systems, but it is no worse than what the car originally was equipped with. If I want top notch sound, I'll hop in my wife's Subaru and crank up the CD player, but it's still not the trip that driving my Rambler is.


Posted By: Monza_1966
Date Posted: Jan/03/2011 at 6:14am
seems like a lot of work to use an old radio. If your just wanting to not see a modern radio, just put it in your glove box. I'm accually putting a deck in my wagon that doubles as a mp3, tv, usb, and memory chip player. I'm going to place it on the ceiling in a modified corvair stereo box. It should be really nice.

-------------
1966 Chevy Corvair Monza
1963 Rambler 880 Cross Country


Posted By: cali201
Date Posted: Jan/03/2011 at 7:24am
I have had both of my Am radios converted to AM/FM with rca inputs on the back as I use my Ipod lots.  Both radios were also increased to output more power.  In my AMX I used a duel cone speaker in the stock location for the "stereo" and on the Javelin utilized multiple speakers in their stock locations.   While it was pricey I could not be happier with what I have, a stock radio that does everything I ask of it. The only way you would know it is not 100% stock is if you take the dash apart and remove the radio which I do not think anyone will do to my car.  A few people who have heard my radio are shocked at the sound of an old AM radio!!  When I first got my AMX I tried a modern radio under the seat but as mentioned try to change the station, etc.   The Metropolitan I am restoring had a modern unit mounted under the dash when I got it.  First thing I did was rip that out and when the car comes back from the paint shop I will be installing a radio I got from a guy in Kalifornia.  It is a Metropolitan radio case (they are very bulky things) with new guts with Am/FM and rca input, new speaker (the speaker on those radios was part of the radio itself!!).  Again I will have a 100% looking stock radio with modern performance (somewhat due to the one speaker, he should have used a duel voice cone speaker which I may swap out)

-------------


Posted By: Chisam
Date Posted: Jan/03/2011 at 9:59am
I just had turnswitch convert my 68 AM/FM. It took about 8 weeks, it is done and on it's way back  now. I won't know how I will like it as the car is put away for the winter and I won't put it in untill sometime in the spring. Maybe a bit pricy but I put a hidden one in from autosound and I just didn't like the way it worked so I sent my AMX radio to  turnswitch to be converted. It is a AM/FM and some said don't change it as it is some what rare but I wanted it to work good.

-------------
1968 AMX 390 4SP


Posted By: sidewinder
Date Posted: Jan/03/2011 at 10:19am
Let us know how you like it...do you plan to bench test it when it comes back?   I have the same situation with mine.  Original AM/FM....crappy mono sound....   I have two AM/FM radios so I do have a back-up.   Can I ask what they charge??   Thanks....

Chuck Page


-------------
Chuck Page ,AKA Sidewinder
1968 "BLACK CHERRY" Javelin
Previous owner of 2013 Heritage Cup winner 1970 BBO AMX




Posted By: Chisam
Date Posted: Jan/04/2011 at 1:50am
Turnswitch will either repair or do a conversion to your radio. They explane what they can do on their site.  They gave me a cost of repair, 150.00 to 200.00, I had the conversion done and shipped back it was 430.00. They seem to be good to deal with, they reply emails right away, let me know when they received it ,when the work was done and they weren't fussy how it was paid for. It may sound like a lot but I did try the hidden radio and while the sound was good, just not easy to change or adjust while driving. I do like the dash speaker that custom autosound has, two speakers that replace your stock speaker, fits in the stock location and a lot better sound with no cutting of the dash.    

-------------
1968 AMX 390 4SP


Posted By: nali
Date Posted: Jan/04/2011 at 2:44am
The goal of my hack is to simply use a mp3 player on a vintage radio .
You can find the kit for 100 $  . Mine cost 5$ , the most expensive part is the plastic box .
It wont change any AM mono radio to a Fm stereo  :P
I m quite a former electronic ing , I know the limitations of my hack . The only good side is it s easy to do for about everyone . Just 3 or 4 wires to solder .
It s an easy , efficient way . Don t ask much for 5  $ .
I made also a nice 4 way active filter ...  With Fenton 6 " , Aerogel 4" and Vifa 1 " titanium tweeters .
Central is a mix 300 -3000 with AOP and 24 db filter .

So I know this has limitations .
It cost 5 $ when other sell 100 $ for the same thing .

Just enjoy .

Edit : just avoid crossing grounds . This will kill everything .


-------------
No more car :)
Maybe a 1965 Ambassador Coupé someday .. If I can find a cheap one.


Posted By: ronilevi
Date Posted: Feb/23/2011 at 1:55pm
Hi again all!

I just wanted to share my success with this hack and let you guys know that it works really well for a $1 hack. I had to recap my radio to get it functioning at first but once that was done, I was able to get this going really quickly. I have only recorded a quick video of it in action (which I will post here) but I am working on documenting it (and making it a more permanent solution) and then posting it to instructables for more people to enjoy.

Thanks nali for posting this topic and MUCH thanks to gryzynx for clarifying all the murky and unclear points in applying this.




Posted By: nali
Date Posted: Feb/23/2011 at 8:35pm
Of course it works :)
Glad to see someone finally dare cutting and soldering in an old radio to try this .
Thanks for the thanks Big smile


-------------
No more car :)
Maybe a 1965 Ambassador Coupé someday .. If I can find a cheap one.


Posted By: nali
Date Posted: Jun/30/2011 at 3:10am
As I help a member making the modification , I read this tread again and will add a few modifications .

Refering to post from ronilevi :
Yes , a condensor will change the frequency response .
It will work like a low pass filter . The cut off ( not sure it s the right word ), with 220 ohm and 0.05 uF , will be a 6dB filter at about 15000 Hz . So I think Gryzynx made a mistake :)

A 33uF will give a 21 Hz low pass filter , it s a common value and will be better .

As Gryzynx said , a condensor on the "hot"  wire won t help while for ground issues . But a condensor on the ground wire will . It has to be 2x the value of the ones on the hot wire . So let s say a 68 uF , with 220 ohms resistor .

So now you can plug the mp3 player on a charger safelly while pluging it on the radio .
For RC filters , see http://sim.okawa-denshi.jp/en/CRtool.php

http://www.servimg.com/image_preview.php?i=758&u=12474091">



-------------
No more car :)
Maybe a 1965 Ambassador Coupé someday .. If I can find a cheap one.


Posted By: electroleyden
Date Posted: May/17/2016 at 2:31pm
hi all,
i am still trying to grasp how this is supposed to be connected. So the way i understand it is:

Connect the ground coming from the radio and the sleeve on the jack to the ground side of the volume,

connect the wiper wire from the radio to the wiper on the volume,

connect the positive from the radio to one side of the shunt in the jack,

connect the ring and tip  on the jack each to a resistor, and then the resistors to each other,

connect the resistors to the positive side of the volume.

is this right?


Posted By: nali
Date Posted: May/17/2016 at 10:19pm
Hello, and welcome to the forum.
Remember it's a "fast and ugly" way of doing, so you have to be careful, a bad wiring may destroy your devices.

As everything about electricity, it's not really difficult, but this is full of "in your case, it won't work" :)
So I hope you understand a bit.


"Connect the ground coming from the radio and the sleeve on the jack to the ground side of the volume,"
Yes, and no :)
There are 2 ground in fact. The ground for the power supply of the radio, which is the same as the main car ground : chassis, body, etc.
The other ground is the ground for the audio signal, inside the radio. Most of the time, they are the same.
But basically, I'll answer YES.


"connect the wiper wire from the radio to the wiper on the volume,"
I don't understand this. English is not my native, andfor me wipers are used only when it rains :)
Maybe someone will understand.

"connect the positive from the radio to one side of the shunt in the jack,"
The positive from the radio ? You mean the +12 volt ? No way !!!


"connect the ring and tip  on the jack each to a resistor, and then the resistors to each other,"
The goal here is that most of old radios are not stereo, but mono. So the resistors are used to add left and right signals coming from a mp3 device to a single channel.
In case your radio is stereo, each tip of the jack will have to go to the half of the volume button.


"connect the resistors to the positive side of the volume."
I don't like the "positive" term. It's source of confusion between power supply and audio signal.
But if I understand correctly what you mean, my answer is YES.


You don't seem to know much about all this, so you are right to ask ! :)
So before wiring anything, I strongly suggest you understand really what is to be done.
Or ask a friend with a bit more of knowledge.

I'll be glad to help you, but it will be useful to understand what device you plan to plug on your car radio.
And especially what your car is, which year and which radio model.
For example, since there's no indication on your profile, I can't guess which car you have. If it's an english car, with positive on the boby, some ajustements may be needed :)
If it's a Rambler / AMC, no needs.

If you make clear pictures of the inside, I'll show you exactly where to solder the wires.

Whatever you do, before details, I STRONGLY DISCOURAGE you to plug your Mp3 player / Iphone /Android  on the +12 volt adaptor for the electric lighter, while it's also connected to the radio.
There are (few) chances to destroy it.
So let's play it safe :)

Yours.

Philippe / Nali
 




 

-------------
No more car :)
Maybe a 1965 Ambassador Coupé someday .. If I can find a cheap one.


Posted By: electroleyden
Date Posted: May/18/2016 at 7:39am
This is what I am thinking you are talking about


Posted By: nali
Date Posted: May/18/2016 at 4:00pm
I'm not sure this will work. It depends how the 1/8 adaptor is inside, and there are so many models that you have to check it with an ohmeter.
So I have difficulties to understand your (nice ! :) ) schematic.

The button volume is the one inside the radio unit, of course.

There are different parts in the radio. The radio AM recevier, maybe a tape player, and they deliever the audio signal.
Then there's the button volume, it's goal is to ajust how much of this signal is send to the internal amplifier.

So, when nothing is pluggued in the 1/8 jack, the Source going to the Source on the button is the same as original. There's no modification needed on the Wiper side, which is connected to the amplifier.

So, basically, when nothing is plugued in the 1/8 jack, your radio should work as usual, the signal coming to the Source side of the volume is the stock one.
It's only when you plug your Mp3 player that the signal comes now from it.

Sorry, it's not so easy to explain while writing, and english is not my language  :)



-------------
No more car :)
Maybe a 1965 Ambassador Coupé someday .. If I can find a cheap one.


Posted By: Johnny
Date Posted: May/18/2016 at 10:40pm
I have a 63 American convertible that I wanted to add sound to. The correct Rambler radio internals were junk, it was not push-button and the speaker was toast.

First I went to Walmart and picked up a pair of motor cycle/ATV 12 volt powered speakers that accept an MP3 player input. The pair of small round speakers fit nicely into the original oval speaker opening under the dash. I stored the power unit and MP3 in the glove box.

Next I routed one side of the speakers power cord thru the on/off volume control in the radio. Now, with the MP3 and power unit turned on, I can turn the sound on/off with the radio switch and have great sound coming out of the dash speaker outlet with the radio lit as if working.

I then took the push buttons from a non-Rambler radio and added (bonded) them to the existing radio. I now have a nice looking period correct push-button radio that can play any tunes I program on the MP3 player. 

Kind of neet to pull up to a cruise-in with Wolf Man Jack coming out of the radio. (And, yes the sound is pre-set using the speaker power volume control)



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