The PHILCO Phorum
Philco 70 Cathedral Speaker - Printable Version

+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Philco 70 Cathedral Speaker (/showthread.php?tid=11053)

Pages: 1 2 3 4

RE: Philco 70 Cathedral Speaker - Arran - 12-09-2014

(12-05-2014, 10:05 PM)Steve Davis Wrote:  
Quote:I hope he will, he did not claim it was working....
Mike, The guy responded that he was unable to test the speaker so he sold it as-is. Well, I checked his other auctions and he has several radio related items listed, that tells me he must have some knowledge about this sort of thing. So I just don't believe his story. I think he had tested the speaker and was dumping it on Ebay.
Other Mike, I have been studying the pictures of your winding machine, I will have to make one. A pulse width speed control would work much better. I also need to build some sort of fixture to press out the pole piece. I'm not sure if I want to use a hydraulic jack or just a large bolt.
Steve
 Pressing out the pole piece is the easy part, pressing it back in so its straight is another matter, though not too difficult with a proper press. I can't imagine that they needed much force to press them together but who knows, at least they didn't weld them in too like an RCA speaker.
  I think that if it is a universal style brush motor you could probably limit the voltage to control the speed, like with a variac. For an AC only motor that involves using a variable frequency drive, which is out of the question for this sort of thing. A fellow on you tube used a cordless drill, which has a speed control built in, with gears I think, and rigged up a counter to count the number of turns, it usually is not a problem finding a good cordless drill to butcher for this, most people toss them out after the battery dies.
Regards
Arran

RE: Philco 70 Cathedral Speaker - morzh - 12-09-2014

There is article on how to control a unimotor.

And, cannot be use unloaded.

RE: Philco 70 Cathedral Speaker - Steve Davis - 12-09-2014

My plan for the winder is to use a cordless drill that I have that has a bad battery. I'm going to try to remove the trigger speed control and modify it to a foot control. I will use a 12 volt battery to power it.

I going to have to order some 36 ga. wire. I have a roll of 37 ga. with about two pounds on it that I bought at a flea market. I first thought I would go ahead use it but, I decided to order the correct size. I don't want to have to do this over.

Steve 

RE: Philco 70 Cathedral Speaker - morzh - 12-09-2014

Steve

AWG37 has 25% less ampacity than AWG36. Considering that for whatever reason the AWG36 got bad, it will be even more the case for AWG37, so, yes, go with original gauge.

RE: Philco 70 Cathedral Speaker - Steve Davis - 12-27-2014

I bought some 36 AWG magnet wire on Ebay. The wire arrived in a few days but, I have a problem, the insulation is much thicker. The original and the new wire both measure .005, stripped but, the original wire measures .0055 with the insulation on. The new wire measures .007 with the insulation. Well, I decided to go with it. The bobbin is about a quarter of an inch smaller than the poll frame so, I cut larger fiber discs and glued them on the ends of the bobbin so I could get more wire on the bobbin.

I made a simple winder and wound the coil.




[/url]
[Image: http://i985.photobucket.com/albums/ae335/SteveinMissouri/Internet%20Stuff/107_0034.jpg]


I wound the bobbin as full as I could but, the resistance read 2450 ohms. I don't want to rewind the coil so, I may need to add a few hundred ohms resistance.

[Image: http://i985.photobucket.com/albums/ae335/SteveinMissouri/Internet%20Stuff/107_0038.jpg]




[Image: http://i985.photobucket.com/albums/ae335/SteveinMissouri/Internet%20Stuff/107_0039.jpg]

Now, I just need to recone the speaker.


Steve





[url=http://s985.photobucket.com/user/SteveinMissouri/media/Internet%20Stuff/107_0034.jpg.html]

RE: Philco 70 Cathedral Speaker - morzh - 12-27-2014

Steve

I am sure for the speaker's own performnce this is not critical, and a few hundred ohm resitor in series will take care of DC voltages.


Since your bobbin is full, don't forget to wind the humbucker before you ...oh ....you have already assembled it.
Does 70 even use humbucker? 20 does....

RE: Philco 70 Cathedral Speaker - Ron Ramirez - 12-27-2014

Moved to Philco Electronic Restoration since we are now discussing the restoration of a speaker, no longer one that is for sale online.

RE: Philco 70 Cathedral Speaker - 462ron - 12-27-2014

Hi all, I have a question concerning the method used in winding a coil. Say you start on the left side of a coil form and proceed to the right. Once you get to the right side do you (A)..keep winding the second layer from the side you ended the first layer, the  right side in this example, and move left or do you (B)..end the first layer on the right and then immediately return to the left side and start the second layer and continue moving right again? Sorry if this sounds confusing but I wonder if this affects the inductance at all? Thanks

Ron

RE: Philco 70 Cathedral Speaker - Steve Davis - 12-27-2014

Mike, there is no humbucker.

Ron, the first layer is wound from one side to the other, say from left to right, the second layer would be wound from right to left.

Steve

RE: Philco 70 Cathedral Speaker - 462ron - 12-27-2014

Thanks for the info Steve.

RE: Philco 70 Cathedral Speaker - Steve Davis - 12-28-2014

The speaker has been reconed.
[Image: http://i985.photobucket.com/albums/ae335/SteveinMissouri/Internet%20Stuff/107_0053.jpg]


Steve





[url=http://s985.photobucket.com/user/SteveinMissouri/media/Internet%20Stuff/107_0053.jpg.html][/url]

RE: Philco 70 Cathedral Speaker - Arran - 12-28-2014

(12-27-2014, 07:30 PM)462ron Wrote:  Hi all, I have a question concerning the method used in winding a coil. Say you start on the left side of a coil form and proceed to the right. Once you get to the right side do you (A)..keep winding the second layer from the side you ended the first layer, the  right side in this example, and move left or do you (B)..end the first layer on the right and then immediately return to the left side and start the second layer and continue moving right again? Sorry if this sounds confusing but I wonder if this affects the inductance at all? Thanks

Ron

Hi;
  No you work your way back and forth across the bobbin, left to right, then right to left, other then the leads which are buried under the wrapping. Field coils, unlike RF and oscillator coils, are not that fussy about how they are wound, as long as the wire gauge is think enough and the coil has enough turns to be close enough in terms of inductance, the object here is to produce a magnetic filed, and block the 120 cycle AC ripple.
Regards
Arran

RE: Philco 70 Cathedral Speaker - morzh - 12-28-2014

..and if possible to meet the resistance of 3.2K to keep the DC Volts the same so you don't have to add a resistor in series. But if you do, it is not the end of the world.

RE: Philco 70 Cathedral Speaker - Arran - 12-28-2014

(12-28-2014, 09:17 PM)morzh Wrote:  ..and if possible to meet the resistance of 3.2K to keep the DC Volts the same so you don't have to add a resistor in series. But if you do, it is not the end of the world.

 It may or may not make a difference, if the wire is thicker the DC resistance may be less but the inductance may be the same, I somehow doubt that the DC resistances were that consistent from speaker to speaker anyhow. The only way to find out is to test it, if the B+ is too high that's very easily corrected, in terms of hum it won't make any difference at all.
Regards
Arran

RE: Philco 70 Cathedral Speaker - Steve Davis - 12-29-2014

Quote: It may or may not make a difference, if the wire is thicker the DC resistance may be less but the inductance may be the same
Quote:The wire I used is thicker only because the insulation is thicker, the wire without the insulation is the same diameter. This caused the coil to have fewer turns, lower DC resistance and probably slightly lower inductance.


Steve