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project help with toy IC boards


CALAHAN
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i once read about the LM390 which is a low voltage high power amplifier. i have not myself used it but it may come in handy in this circuit. i've used the TDA2822M and it works well. i had made a small amp for my walkman using the TDA2822M driven from 4.5volts (3 AA batteries), well if u use small speakers then the quality is good and u won't find much distortion. i leave it up to the user and other senior members to decide which will be better. ;)

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Hi Sukhbinder,
I use LM390 audio amps in my clock radio and in a signal generator. It is too bad they have been discontinued for 10 years. They are like an LM386 but with a higher output current and bootstrapping of the driver transistor for a much higher voltage swing. Its minimum supply is 4.0V.

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I've had to take a break from these electronic projects for a bit for a couple of reasons. But, I did go into Radio Shack and buy one of these 741 Op Amps. There is no data on the back of the package, so I have no idea if it is even close to doing what I want. I have not pulled up the internet info on it yet either, and when I do, I'm sure there will be a completely different configuration of capacitors and resistors that will need to go with it from what is in any schematic I may find.

As for my 3v toy chip amplification project, I want to try this TDA2822M to see if it works with my 3 volt power supply feeding both the amp and the circuit board (it did not work with the MC34119 which was a waste of time and money). Of course though I have to order one of these things, and this takes time, then I have to get time to pull the bread board out and all of my alligator clips - again.


Once I get one of these amps down where it will work, then I can re-create more for my toy prototyping projects. I will try audioguru's schematic for splitting the 9 volt battery to feed the 3 volts for the toy chip, with the other voltage of the battery going into one of these amps.

I have tried about 3-4 different amp options and none of them have worked with my project yet. The only success I have had so far is when I powered a 386 off of a 9 volt separately from the toy IC which was fed off it's own 3 v supply.  This configuration takes up too much space of course, but I have not tried the 9 volt split to power both yet as time is a commodity I have little of. Perhaps this weekend I will attempt all the different configurations with fresh batteries.

The second project I was working on which was amplifiying the Radio Shack chip recorder, both off of one 9 volt battery, has also been put on hold until I can get this 3v toy IC chip amp working.

Is there any specifics I need to know, or a special schematic I need for this TDA2822M before I order a few of them?

Bruce (CALAHAN) 

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Hi mvs sarma, your are right the TDA2822M is a very versatile IC and i've seen a number of computer multimedia speaker brands in INDIA which use the TDA2822M as the main power amp. although its rated as a  1W/ch IC the speakers show a rating like 220W PMPO (this PMPO thing is all rubbish, never go for the PMPO rating always check out the RMS ratings for amps, by the way PMPO ratings are not recognised as a standard by the electonics and electrical engineers). i had seen a 2.1 speaker system which uses a TDA2822M for the satellites and a TEA2025/KA2206 in bridge mode for the subwoofer. quite a small and cheap contraption but works well for low budget needs. ;)

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i am totally in line with audioguru's philosophy-- there were times when power was generally indicated (specified) as RMS watts. --over times the pmpo took over. in fact the transformer used in the multimedia speakers is too small( if not three small) it coud deliver few ma at 12V  finally the output power could not be greater than 400 to 800 mW per channel as the input DC power is 1 watt max

sarma

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