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Norm Leal
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Wed 11, 2012 4:42 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 30802 Location: Livermore, CA
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Hi Ricky
I don't blame you for not understanding the coil. It looks just like a resistor. Notice the resistor looking device with orange, orange, brown, gold bands. That's a 330uh coil. The green one, on end, is another coil.
Looks like Tom used 2.2K resistors in series with RCA jacks. Doesn't seem like 8.2K from here? Value isn't critial. It just keeps from shorting left and right channels together.
_________________ Norm
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Rickey
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Wed 11, 2012 5:17 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 682 Location: Cedartown,Ga. USA
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Norm Leal wrote: Hi Ricky
I don't blame you for not understanding the coil. It looks just like a resistor. Notice the resistor looking device with orange, orange, brown, gold bands. That's a 330uh coil. The green one, on end, is another coil.
Looks like Tom used 2.2K resistors in series with RCA jacks. Doesn't seem like 8.2K from here? Value isn't critial. It just keeps from shorting left and right channels together. Thanks, Norm. Do you make the coil, or salvage one?
_________________ Rickey N4IDQ "Turn your radio on!"
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35Z5
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Wed 11, 2012 5:33 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 11778
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Hi Rickey I suppose you could wind coils, but recently bought them in bulk from a offshore seller on ebay, have like $6 in 50... Send me a PM with address & I can send you the coils... If you need most of the components, Bill Hamre also has a parts kit... Hey Norm, those audio resistors are 8.2K 2%, there is a very hard to see gray band on the end... Still I've found something in the range of 1-1.5K to be as good as anything... The breadboard has a old pair of 1K that measure closer to 1.2K, didn't want to chop up new resistors I could use elsewhere... http://amradio.freeiz.com/transmitter/386txled.jpgSchematic with wallwort P/S & LED tuning indicator... http://amradio.freeiz.com/transmitter/386txps.jpgTom
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Rickey
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Wed 11, 2012 6:07 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 682 Location: Cedartown,Ga. USA
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Thanks Tom, pm sent.
_________________ Rickey N4IDQ "Turn your radio on!"
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Norm Leal
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Wed 11, 2012 6:55 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 30802 Location: Livermore, CA
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Tom
I must need a new monitor. From here I see red, red, red, gold.
_________________ Norm
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35Z5
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Wed 11, 2012 10:06 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 11778
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Norm Leal wrote: Tom
I must need a new monitor. From here I see red, red, red, gold. Actually Norm if someone told me the end bands were gold, I could see their view... Gray is difficult to distinguish on the blue body... Tom
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Rickey
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Wed 11, 2012 10:15 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 682 Location: Cedartown,Ga. USA
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Tom, on the schematic, which one is the potentiometer ? I see the trimmer, just a little confused.
_________________ Rickey N4IDQ "Turn your radio on!"
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35Z5
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Wed 11, 2012 11:34 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 11778
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The center tap of the pot connects to the .1 that couples signal to pin#2 of the LM386... Audio signal enters through the pair of 10K to one leg & opposite leg connects to ground... It's a common voltage divider circuit, just vision the center tap(arrow) being able to move toward or away from ground(which is exactly what it does) to allow more or less signal to enter the LM386... Value isn't critical, you can reduce to as low as 5K as long as the input resistors are also kept at approx 20% of the pot's value... Repost of schematic so it's easier to visualize...  Tom
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Rickey
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Thu 12, 2012 1:03 am |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 682 Location: Cedartown,Ga. USA
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Thanks,Tom.
_________________ Rickey N4IDQ "Turn your radio on!"
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radiorich
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Fri 13, 2012 6:28 am |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 11271 Location: Omak,wa,usa
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Hello Guys, Ya count me into let me know what the kit will cost Sounds fun
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AndyC
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Fri 13, 2012 6:42 pm |
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Joined: Jun Fri 29, 2012 2:13 am Posts: 116 Location: Vancouver, WA
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Sounds like what I need. Where do I send the money?
Thanks,
Andy
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K4YDO
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Wed 18, 2012 12:44 am |
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Joined: Nov Mon 28, 2011 2:55 am Posts: 935 Location: Florence, SC 29506
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Thanks to Tom and Bill and anyone else who may be involved in this project. Mine worked perfectly the first time I applied power. It seems to rival much more complex circuits. Now on to a 120 power supply and a case.
Ed
Attachments: |
File comment: It would have been neater except that my dog kept bothering me. Oh yes, I don't have a dog, so substitute another excuse here.

LM 386 Xmtr (Small).JPG [ 94.15 KiB | Viewed 8198 times ]
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_________________ It is useless to have a lot of spare parts if you canāt find what you need !!
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35Z5
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Wed 18, 2012 1:37 am |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 11778
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Quote: It would have been neater except that my dog kept bothering me. Oh yes, I don't have a dog, so substitute another excuse here. Looks fine to me, oversize components on a small board can be a challenge to work with... Tom
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rocketeer
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Thu 19, 2012 3:01 am |
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Joined: Mar Tue 30, 2010 2:24 am Posts: 8969 Location: Lehighton, PA.
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I'm finishing up the one I'm building for a friend and the 0-50pf trimmer/capacitor is bad. Anybody have a spare?
Thanks, Larry
_________________ kb3wbb
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bill hamre
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Thu 19, 2012 3:52 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 2188 Location: aston, pa, usa
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I'll mail you a trimmer
_________________ "All glory is fleeting" - George Patton
KB3QNN 73
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rocketeer
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Thu 19, 2012 4:20 pm |
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Joined: Mar Tue 30, 2010 2:24 am Posts: 8969 Location: Lehighton, PA.
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Thanks Bill.
Larry
_________________ kb3wbb
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radiorich
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Fri 20, 2012 3:02 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 11271 Location: Omak,wa,usa
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hello tom, I wondering if there is going to be a kit offered this is a great unit for me to build as a gift
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35Z5
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Fri 20, 2012 3:24 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 11778
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Hi Rich
Anyone wanting a kit should contact Bill Hamre, he stocks a supply of parts...
Tom
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Sam T
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Fri 20, 2012 3:45 pm |
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Joined: Feb Sun 27, 2011 4:23 am Posts: 543 Location: Alabama Gulf Coast 36551
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Bill, Where did you source that nice ceramic/mica trimmer? All I see anymore are the microminiature plastic things.
-Sam T.
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bill hamre
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Post subject: Re: LM386N MK-XI BCB Transmitter Posted: Jul Fri 20, 2012 6:20 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 2188 Location: aston, pa, usa
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Sam,
Dan's small parts and kits.
Bill
_________________ "All glory is fleeting" - George Patton
KB3QNN 73
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