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What kind of battery should I use for this radio? Answered

I've been rebuilding an old radio and want to make it entirely wireless. It normally has a 120 volt input with a 15 watt consumption. What kind of battery can I use? Can I make it rechargeable?

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iceng

Best Answer 7 years ago

I take this is like a collectors radio even with electron tubes.
Can you give us a name brand please ?

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funnylooking5iceng

Answer 7 years ago

Its a Thomson Collectors Radio, so not actually old, just a reproduction. It only lists the inputs and not the outputs.

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funnylooking5

7 years ago

I opened it and measured the power supply after it goes through what looks to be a transformer. It has 8.4 volts AC. DC wouldn't register at all so I think it's saf to say it's not a rectifier. Since it's in AC, there's no way I could hook a battery to it without a bulky inverter, right? Would hooking up something DC really be that bad?

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icengfunnylooking5

Answer 7 years ago

It would not , Is this a tube Radio Please ?
Battery selection makes a difference without and with tubes.

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funnylooking5iceng

Answer 7 years ago

Its a reproduction, so no tubes. I've measured the voltage at a separate point, and it measured either 20 volts AC or 9 volts DC. Could there be a rectifier on there, and I just can't find it?

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icengfunnylooking5

Answer 7 years ago

It could also be a mixed signal.
Can you post a picture ?

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funnylooking5iceng

Answer 7 years ago

I measured the voltage coming from the transformer to the ground. It registered 5 volts DC and 10 volts AC. I did, however, manage to power the casset player, along with the stereo and speaker through a 9 volt battery. Doesn't this mean there HAS to be a rectifier in there, so I just have to find it, and hook up batteries after it?

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icengfunnylooking5

Answer 7 years ago

Yes it does and you have already found the DC bus, go ahead and run it on a
nine volt battery. The AC could just be the floating ground.
You would need a technical grounded in AC & DC circuits to determine that.

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funnylooking5iceng

Answer 7 years ago

The problem is though, ONLY the casset player will run when I have it wired to there. Neither the AM or FM radio will. It's because, I failed to mention, I wired it straight to the casset motor. But there should be a better place to wire it, that i just haven't found, right?

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icengfunnylooking5

Answer 7 years ago

Limiting our info only gets U half answers (Grrrrr).
Good pictures might help us see the bridge rectifier you seek.

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funnylooking5iceng

Answer 7 years ago

Heres all the information I have:
When measuring the connection from one of the wires leading from the transformer and the ground wire, it reads 5 volts DC, 10 volts AC (I hope I didn't mix that up). The main lines only read 8.4 volts AC, and won't do anything when a 9 volt is applied to it. While, functioning, the cassette player reads 9 volts DC and 20 volts AC. The radio functions by normally player by either FM or AM until a cassette is entered. When powering the motor with a 9 volt battery, it will power the entire system, but it bypasses the system that detects if there is a cassette in the player. Immediately after where the power supply connects to the circuit board, there is a capacitor, and what may or may not be a regulator under it. This, to me at least, means that there should be a rectifier already on there.
I'll supply pictures as soon as I can. Thanks for your help.

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icengfunnylooking5

Answer 7 years ago

There must be a single diode feeding the cassette player to prevent motor
noise from traveling backward to the radio DC bus and distorting the radio
when recording off the radio. I presume it can record a radio program, yes ?

Is the circuit PCB made with through hole components ?
or made with ( SMD ) surface mount components ?.

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funnylooking5iceng

Answer 7 years ago

Its an SMD. The cassette player will not record anything, only fast forward and play. The cassette player is in an obnoxious place for trying to view much of the board and nearly impossible to take out, so the pictures may be awkward looking. I'll try to get enough angles to look at them all.

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icengfunnylooking5

Answer 7 years ago

That does not make sense as far as motor noise.
Because as you say when the cassette plays the radios cannot,
therefore back motor noise is avoided !
The logical thing left is that the cassette voltage is lower then the radios voltage.

Can't come up with any other thoughts right now.

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funnylooking5iceng

Answer 7 years ago

These are the best pictures I could get. The awkward ones are where the energy input leads.

DSCI0001.JPGDSCI0003.JPGDSCI0005.JPGDSCI0006.JPGDSCI0007.JPGDSCI0008.JPGDSCI0009.JPGDSCI0010.JPGDSCI0011.JPGDSCI0012.JPGDSCI0014.JPGDSCI0015.JPG
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icengfunnylooking5

Answer 7 years ago

Good pictures tough spots as you said.
I can see the xfmr output blue AC wires, is that metal foil around them ?
Is there a third wire out of the xfmr ??
Where the blue xfmr wires connect to the PCB is close to the volume control and the audio amplifier.
There should be two or four diodes ( see pics ) they probably will not be arranged as below.
You should measure and be able to insert a battery at the Plus and Ground points.

Diode.jpgbridge.JPG
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funnylooking5iceng

Answer 7 years ago

There's only two xfmr wires. II found four of those lined up vertically. All points of them measured 5 volts DC and 10 volts AC. I tried 3 C batteries to power them. I wasn't sure which points would have been Plus and Ground points, so I tried a combination of all of them. It seems like I powered the speaker and only that.

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funnylooking5funnylooking5

Answer 7 years ago

I found the sweet spot on the bridge and have it all planned out from here. Thanks so much for you help and patience.

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Re-design

7 years ago

If this radio has a power transformer then you can't run it on batteries without modifying.

If this radio is what is called AA5 design where there is no power transformer and the tube filaments are in series to reduce the voltage to what they need then you could "probably" run this radio on 110 volts dc.

google ac/dc radio and aa5 radio for more info.\

Ask this question on this site for some REALLY good answers.


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orksecurity

7 years ago

The best solution would probably be to get a radio designed to run from batteries.

The best solution to making this radio run from batteries might be to figure out what the output of the radio's power supply stage is and replace that whole stage with a suitable battery -- where suitable means "the right voltage, long enough to get useful listening time out of the radio before the batteries run down." Except that -- well, if a unit is designed to run off batteries, it expects that batteries *do* run down, and will work from the nominal voltage down to a considerably lower voltage; I'm not sure that a plug-in radio, which assumes that a specific voltage will always be available, will be as forgiving.

The inefficient but no-alteration-of-the-radio answer would be a 12V gel cell powering an inverter to produce 120V. Gel cells are basically small(ish) lead-acid batteries; they are rechargable and you'd also have to get a charger. Massive overkill for your needs, though.

The off-the-shelf version of the inefficient answer, as I said in response to another recent question, is to go into an auto supply store and ask them about "chump starters". These are basically a gel cell, a charger, a pair of jumper-cable clamps so you can use it to jumpstart your car when you've let the battery run down (again), and -- in the fancier units -- an inverter. Even more massive overkill for your needs, but a much more versatile solution and absolutely no design work needed -- just plug in and turn on.