The PHILCO Phorum

i have this am/fm zenith running now and its been in use by the wife while doing things in the kitchen.
we were watching some youtube vids on various things and came across D-Labs and Mr Carlson's Laboratory where aux jack mods came up on tube radios.

Here ,,, Terry at D-labs shows how he did an aux jack to a console set and he did up a schematic.


in my case i want to add the jack to the cardboard back of the radio... so it wont actually be mounted to the metal chassis.

i am checking to see if i have a jack that makes and breaks contacts when you slip your modern day smartphone head phone jack into the slot
this way i wont have to add a toggle switch to select radio signal or smart phone.

in this D-Labs vid, terry mentions a 10k resistor used to simulate the headphones which is tied to this jack.  he is mounting his to the chassis though,, 
https://www.youtube.com/watch?v=j8YeJ0T3DpI


can someone help me tie a jack into this radio schematic?,, a sketch or edit to the pic i am posting?

i think i simply intercept the left side of the volume on the attached print and tie this to my two center contacts of my jack.  if its the type that breaks contacts inside,, then i wont need the toggle.  

there were a lot of warnings about doing this to transformerless sets but i think thats because its assumed you are mounting your jack to the metal chassis,, which will not be the case for me.

my vol control is in the lower right of the print just above the filter caps......

[attachment=17992]
Looking thru my radio repair notes, found info on a Z set I worked on in 2011. Has a factory phono jack. The case looks a lot like your set hope this info helps. A link to Phils old radios for more info.   https://antiqueradio.org/iPodAdaptor.htm

Posting a link for 2 different RCA sets both with a factory plug. sets are AM only. Good playing radios.  http://www.nostalgiaair.org/pagesbymodel...014894.pdf      
http://www.nostalgiaair.org/pagesbymodel...015948.pdf

so... i see that now,, i dont have a phono input on my Z and it took me a minute to see that in the diagram you posted, its a slider switch.

here this guy is also agreeing that within the modern smartphone headphone jack there is a left and right speaker signal then deal with the ground & shield as required.
he is agreeing that you join up the modern cable left and right with inline 1kohm resistors on each wire so your smart device interior electronics see's a load to simulate ear buds.

in this vid,, there is an OEM toggle switch so to speak by way of how the radio was designed.
https://www.youtube.com/watch?v=kL94do8x1-g

in my case i hope to find the jack that acts as contacts so when the cable is pulled out, i am in "radio mode", then when the cable is inserted, i am in ipod mode.

there are lots of discussions on isolation transformers as well incase you want an insurance policy against the possibility of a hot chassis.,, this gets into the discussion of earthing vs grounding vs floating chassis etc...

in m case i will mount my jack to a non-conductive surface ,, this way i simply intercept the wire that is tied to my vol control.
what i know is we dont intercept the wiper..........
we intercept what is called the "high side" of the vol control. so i think that means that looking at the front side of the vol control, you would always use the "LEFT" terminal lug.

links with some more info  http://www.circuitbasics.com/how-to-hack...hone-jack/     https://electronics.stackexchange.com/qu...lor-coding

I would not attempt to add an input jack for a cell phone, or other device, without using an isolation transformer, hot chassis or not it's still an Ac/Dc set. Some phones and notepads use metal trim as an antenna, touch the phone, and touch something grounded at the same time, whilst the phone is plugged into an Ac/Dc radio and you could get zapped.
Regards
Arran

i agree ,, now i am down the rabbit hole of impedance matching that xfrmr

i have to do something though,, the wife really plans to work this set a lot.

david,
i am thinking i should duplicate that headphone circuit and graft it into my zenith, then proceed to the Aux jack install.,, then again, maybe there is a reason this set / chassis number *does not* have a headphone jack at all.

(12-19-2018, 06:46 AM)Arran Wrote: [ -> ]I would not attempt to add an input jack for a cell phone, or other device, without using an isolation transformer, hot chassis or not it's still an Ac/Dc set. Some phones and notepads use metal trim as an antenna, touch the phone, and touch something grounded at the same time, whilst the phone is plugged into an Ac/Dc radio and you could get zapped.
Regards
Arran

Not to mention what could happen if your phone is plugged into it's switching charging supply which is also not isolated.

You could use something like this. Have something like this that I use. works great with my MP3 player.  
https://www.amazon.com/dp/B013UECJ3I/ref...B000WVVX6W

she wants to have a smart phone hooked up so she can pipe in spotify or Ebooks while she does her baking and such in the kitchen.

It also works with DW Samsung phone.