Paul, The National LM386 is powered with 4 min to 12 V max. The LM386-4 accepts 5 to 18 V max. -1 & -3 don't give a spec so would not exceed 12V.
Nice little chip. Gain 26 db typ, input resistance 50k, drive 8 Ohms. Audio in and speaker audio out. 73, ron, n9ee/r >From: Paul Plack <[EMAIL PROTECTED]> >Date: 2008/04/27 Sun PM 06:15:30 CDT >To: [email protected] >Subject: RE: [Repeater-Builder] Re: ADI 247 for a link radio > >I don't know if Radio Shack still even sells them, but over the years I've run >into a store and bought an LM 386 audio op-amp and a pre-etched prototyping >board to throw together an audio "buffer" for applications such as this. The >chip draws just 4 ma at idle, is optimized for audio use with low parts count >(just add two capacitors,) works with high-Z inputs and 8-ohm outputs, and can >provide all the gain you need if configred properly. When used to drive a >speaker, the output is coupled through a large electrolytic cap. If you're >driving a 600-ohm load, you can reduce this to .5 uF or less. Be careful of >"sample circuits" published using this chip. I've seen lots of applications in >which the amp was powered off a "12 volt" rail that could actually be 14 >volts; the chip is specified, I believe, for an absolute max of 12 VDC. If you >have a regulated DC stage at 8, 9 or 10 volts, that's perfect. 73,Paul, AE4KR >From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of >Eric Lemmon >Sent: Sunday, April 27, 2008 5:02 PM >To:[email protected] >Subject: RE: [Repeater-Builder] Re: ADI 247 for a link radio > > >Robert, > >Impedance matching is usually a problem when a low-impedance load is >connected to a high-impedance source, which sounds like what you describe. >When you use an impedance matching transformer, the audio level will be >reduced as well as the impedance, and you may not have enough audio. I am >thinking along the lines of an emitter follower amplifier, which transforms >a high input impedance to a low output impedance, but implemented with an >operational amplifier (opamp). > >73, Eric Lemmon WB6FLY > > >-----Original Message----- >From: [email protected] >[mailto:[EMAIL PROTECTED] On Behalf Of georgiaskywarn >Sent: Sunday, April 27, 2008 3:14 PM >To: [email protected] >Subject: [Repeater-Builder] Re: ADI 247 for a link radio > >Eric, >I was actually thinking of some 600 to 1 transformer. Your thinking a >opamp / preamp would work? Really didn't think about giving it more >audio level. Now I am speaking of the TX audio, not RX. So it is >really what the RC210 is offering...not what the ADI is offering. >Eric...you still think it needs an opamp?? >Thanks for the reply, >Robert >KD4YDC > >--- In [email protected] ><mailto:Repeater-Builder%40yahoogroups.com> , "Eric Lemmon" <[EMAIL PROTECTED]> >wrote: >> >> Robert, >> >> I agree- and the audio level needed by the RC210 is probably much >greater >> than what the radio has to offer. An opamp should work for you. >> >> 73, Eric Lemmon WB6FLY >> >> >> -----Original Message----- >> From: [email protected] ><mailto:Repeater-Builder%40yahoogroups.com> >> [mailto:[email protected] ><mailto:Repeater-Builder%40yahoogroups.com> ] On Behalf Of georgiaskywarn >> Sent: Sunday, April 27, 2008 10:29 AM >> To: [email protected] ><mailto:Repeater-Builder%40yahoogroups.com> >> Subject: [Repeater-Builder] ADI 247 for a link radio >> >> Started a project at the end of LAST summer and never got finished. >> Using a ADI247 as a 220mhz link radio. Blew something up in it (in >> looking for cos), sent it off, got fixed, now just getting back to the >> project. *I Thought* I had decent tx audio out of it into the RC210 >> controller hooked to it. However now I barely get a whisper out of my >> tx audio. I can hook a mic to it...no problem with the audio, works >> fine. Almost sounds like an impedance mismatch. >> >> Ideas? >> Thanks, >> Robert >> KD4YDC > > > Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
