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 Post subject: Replacing phonograph with mp3 player
PostPosted: Dec Fri 30, 2016 6:07 am 
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My Truetone D1145 is in working order now after recapping and some other work. I have pretty poor reception, but thats fine. My big goal is to connect an mp3 player with bluetooth and some other functions through the phono socket. I tested it with an old walkman and it worked great.

My first thought was just to put the player in the drawer where the phonograph used to be. When I noticed the motor socket on the chassis, I got to thinking. How hard would it be to use the motor socket so that turning on the radio also turns on the mp3 player?

The mp3 player is called ndva-1000. It is cheap but it has almost all the functions I want. As a result, if a power surge through the audio cable or motor socket destroys it, I won't be out much. What would it take to use the motor socket to power the mp3 player?

It has an on/off button I would likely have to remove or bypass in some way if I want the player to come on automatically with the twist of the radio knob. I am also thinking of moving the IR sensor on the mp3 player to a place outside the drawer so I don't have to open it to press play or skip or anything like that.

You could say I want to maintain the image of old technology as much as possible. So, spin on switch, use the remote to play music on the hidden mp3 player and so on. Has anyone here tried anything like that? How would you do it?


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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Dec Fri 30, 2016 10:41 am 
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Location: Battle Creek MI
I like doing stuff like this although most the time its me hacking a PA system at school, What kind of powersource are we talking about in the MP3 player? is it an AA/AAA battery or is it one of those players with the LI-PO battery built in? also does it have a physical switch or is it a button? reason i ask is because AA batteries and switches are easier to deal with alot of times.

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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Dec Fri 30, 2016 2:36 pm 
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It is actually a 12 volt dc wall plug. The mp3 player is actually some sort of shelf unit. In actuality, I can't imagine the market for this one is very big since it isn't portable, haha, but it is almost perfect for me.


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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Dec Sat 31, 2016 7:06 pm 
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Nice, that would be a lot easier to integrate a lot less of a risk too... Ive blown up players before on accident because the average players controls and power requirements are very tiny lol. im assuming the phonograph has a single speaker so your gonna need a stereo to mono converter, although the one i posted calls for 10K resistors i normally go for 32K just because my players not cheap, and i don't want to risk anything with higher voltages and whatnot.


Attachments:
stereotomono.gif
stereotomono.gif [ 2.01 KiB | Viewed 360 times ]

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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Dec Sat 31, 2016 7:25 pm 
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Location: Battle Creek MI
For the switch....

if its a toggle switch on the MP3 player (pushbutton toggle or slide switch) I would recommend a latching relay you could use a normal one but having it activated constantly could make it overheat and fry, a latching relay just takes a pulse and latches receiving no power other than when it needs to be unlatched,

if its one of those push button switches then a relay hooked up to some sort of pulse circuit might work,
flip switch -> relay circuit -> pulse -> MP3
forgive me if I'm over complicating things, this is just the kind of stuff i usually do, plus relays are a lot more forgiving when it comes to wiring screw ups than transistors in my opinion.

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DM160,DM70 two of the best tubes ever made.


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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Jan Sun 01, 2017 9:37 am 
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Joined: Nov Fri 25, 2016 4:50 pm
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Well dang, you are proving to be very informative on this one, haha. Thanks a ton.

You can google the name I listed above if you want to see what it looks like. It is pretty generic and cheap. I could post a link, but that seems a little too advertizy/spamy, if you know what I mean.

Anyhow, the output appears to be a stereo 3.5 jack, so I just bought a 3.5 to mono rca cable. I swear they designed that cheap player with me in mind. The components wouldn't work for amyone who wanted true stereo sound.

I guess I need to receive the unit before I can really say what kind of button it is. It looks like just one round button. I thought it might just be one more akin to what is on a tv, but one picture suggested possibly something else.

Any advice on the power? The motor socket is three holes, though only two of them have any contacts. Let me know if you have seen any sockets like this or where to find them, as well as what you might do to wire that mp3 player into it.

I was going to upload photos, but it seems I won't be able to until tomorrow. I guess the above question is kind of hard to answer without photos, but I will leave it there and update later.


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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Jan Mon 02, 2017 2:13 am 
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If the stereo to mono cable doesn't have resistors in the cable to sum the stereo to mono then it may not work right.

May I offer a suggestion which may be a bit more authentic provided this radio is not HI-FI.

Build an LM-386 part 15 AM transmitter. That way you can transmit to the radio and tune it in and if you have or get more antique radios they can all receive the same signal without having to add external inputs to and buy this device for each radio.

The only problem would be if you have radios in multiple rooms as the device could only be controlled in the room it is located in unless you have a whole house audio system with IR control in each room.

If the unit you have has enough space inside, it may even be possible to build the transmitter inside it and use the device's power supply figuring a way to have the control circuitry also turn the transmitter on and off.


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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Jan Mon 02, 2017 7:39 am 
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The cable appears to work really well with a small tape deck, so I think this should work. I even managed to blow the speaker when I tested it without checking the volume or the tape in the deck, which happened to be heavy metal (already fixed the speaker). Of course, we wil see if there are problems with the mp3 unit. It is the only thing missing so far.

I toyed with using a transmitter at once, but discovery if the phono socket changed that plan. Now it seems there is some issue with the radio causing lots of interference with broadcast and short wave signals. I will continue to try to figure it out, but I figure if the phono socket works, I don't need to mess with the transmitter or signal.


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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Jan Mon 02, 2017 3:03 pm 
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The interference could be external to the radio.


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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Jan Mon 02, 2017 5:38 pm 
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Without a doubt that is a possibility. Still have to figure it out.


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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Jan Thu 05, 2017 12:56 am 
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i might buy one of those at some point, seems like a useful bit of hardware and you weren't kidding on how cheap it is. :lol:

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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Jan Thu 05, 2017 6:13 am 
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I got the player unit today. The on/off button works sort of in two ways. First
You have a button that remains depressed while on (kind of standby mode), then you have the ability to turn it on or off digitally using the remote. Not sure if that changes my plan or not.

I can't see any obvious remote ir receiver on the unit, so I would probably have to take it apart to find where it hides behind the face.

Sound is good from the player though I may need to find some way to convert the audio signal to mono before it reaches the phono port. Think I found an adapter, but not sure if it would work. On one or two songs I seem to be missing one of the guitars I think it would normally be on the left speaker channel. So far most songs don't seem to have any problems other than just a couple exceptions. Still pretty satisfied.

The unit is much smaller than I expected. Downright tiny. I can fit it so easily into the phonograph drawer with room for magazines. My only gripe is that there is a repeat function, but I don't think there is a shuffle button. Still enjoying it so far.

Also, my house might be contributing to my lack of stations. It seems My new radio unit has a hard time bringing in one of my usual fm stations. Not a big deal since I didnt plan to really use it that way, but that station is very strong outside in my car, but weak inside. Then again, it is cheap as dirt so maybe the fm receiver is weak.


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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Jan Thu 05, 2017 4:43 pm 
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What you need is this if you prefer building it yourself. Both transformers are 1:1 audio transformers and this will step up the audio voltage some which might make the source a better match for the radio.

Attachment:
Adapter.png
Adapter.png [ 13.92 KiB | Viewed 218 times ]


If you would rather buy an adapter, Edcor has one that will work.

http://www.edcorusa.com/s2m

With that one you will need a 1/8" stereo to RCA plugs adapter cable.

Also with that adapter I don't know what the voltage ratio is so I don't know if the audio voltage on the secondary will be the same, lesser or greater than the voltage on the primary.


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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Jan Fri 06, 2017 7:40 pm 
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I've seen that in the form of an Ipod adapter. It's pretty great. Could you recommend a source for the transformers? The nearest Shack to me does not seem to have them and I seem to recall having a hard time finding a replacement.


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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Jan Fri 06, 2017 7:56 pm 
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Location: Warner Robins, GA
This should work.

http://www.edcorusa.com/wsm_series

You want the 15K to 15K version.

Here's how it is connected up.

Attachment:
Adapter 3.png
Adapter 3.png [ 18.76 KiB | Viewed 197 times ]


Because these are balanced transformers you can have two different options for how much the voltage is increased. One provides a lower increase and the other provides a higher increase


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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Jan Fri 06, 2017 10:00 pm 
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i like this idea, only reason i really use the one involving resistors is because i usually carry the thing around but i might build one of these for stationary use.

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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Jan Sat 07, 2017 6:21 pm 
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This one can be portable if built in a small box.

Plus this will provide a more proper signal level for the antique radios as most were designed around phonos with high output cartridges and the AM detector put out a higher audio level as well than what solid state radios are designed for.

If you've ever noticed, when using the MP3 player you might have had to turn up the volume control more for the same volume level as when receiving an AM station.

My advice would be to use a 1/4" or 1/8" stereo jack as the input jack and either a 1/4" mono or RCA jack for the output. That way it is just plug and play. In this case you can either use two input jacks for the two different input connections or use a DPDT switch with just one input jack.

Here's the updated schematic showing the terminal numbers.

Attachment:
Adapter 4.png
Adapter 4.png [ 19.85 KiB | Viewed 177 times ]


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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Jan Wed 11, 2017 4:55 am 
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Actually, in my case the audio is pretty much as expected. I have both the radio and the mp3 pretty low. It is about the same as using an mp3 player with my car stereo. I am a tiny bit worried that some of my louder mp3s might damage the speaker, so I don't go too loud but it projects well in my living room. Sinatra, Mercury Theater and Paul Harvey sound really good out of it, but if I turn it up much higher I think newer stuff might be dangerous, haha. It seems like only a few songs don't play quite right on it. Even those ones are still good, they just seem to be missing a background instrument or something. It did help when I remembered I could adjust tone too.

I plan to build one of these adapters, but not right away.


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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Jan Wed 11, 2017 4:15 pm 
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Newer music won't damage the speaker as the speaker is rated to at least handle the amplifier's rated wattage.

What you can do to test and see if the volume level is the same is to set the MP3 player to full output volume and tune in a radio station and set the radio to a comfortable volume level then switch to the MP3 player and see if the volume level drops, stays the same or increases.


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 Post subject: Re: Replacing phonograph with mp3 player
PostPosted: Jan Wed 11, 2017 8:07 pm 
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Location: Beautiful Downtown Burbank CA
TheOriginalClassy wrote:
I am a tiny bit worried that some of my louder mp3s might damage the speaker, so I don't go too loud but it projects well in my living room.


You need MP3 Gain. http://mp3gain.sourceforge.net/download.php


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