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stuck on transistors again
i am attempting to build something like this http://hades.mech.northwestern.edu/i...l_follower.gif
for a simple push-pull amplifier.. but I only have one type of transistor. Is it still possible? By the way I found this type of transistor but I wanted to see how I could get it working the simplest way possible. It's from a TV (and whoa my computer monitor just randomly got all stripey pink all over then fixed itself but that's off topic) http://html.alldatasheet.com/html-pd.../2/LA4225.html |
No - you need NPN and PNP
The device you pulled is not a transistor, it is an IC, a small audio power amplifier. |
okay so how do I hook it up properly?
I have the components for it nevermind I got the IC working but no matter what I try.. I can't bias it properly at all D: i tried using some various resistors but it makes no difference wherever i put them D: maybe i still didn't put them in the right place but the gain is still HUGE! with a 5 volt DC power adapter the gain is so huge. it's working... but I need to bias the darn thing somehow... i tried all combinations of resistors here and there... it actually has the most sound without any resistors sadly..\ i'm stumped on why it's not working.. |
Hi,
For the IC to work you need AC coupling caps Cin and Cout as shown on page 3. To reduce gain you need to add a resistor in series from pin 2 to ground. Try 1k ohm. Try to run on higher Vcc, 12volt to 20 volt. Cheers |
yes i got those put on it.... but they do not make much of a difference.. output still sounds blocky and square waved...
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Ok, then try to ad 50k ohm from Vcc to pin 1 and 50k ohm from pin1 to ground.
This will set DC point Vout to approx: gain x Vcc/2. To reduce DC gain to 1x put a cap(20-100uF) in series with resistor that you add in series with pin2 |
ok now it sounds way better but there's a heck of a lot of buzzing!!! sounds like a buzz horn going off i can hear buzzing over 5 feet away!
How do I get rid of the crazy buzzing? and the gain is still extremely high.. My PC's volume is set to 0% and I can hear it clearly coming from the speaker.. |
oh since I can't edit my own post
I wanted to ask.. How exactly do I seriously lower the gain of this amplifier chip? I tried putting 12 volts for it for a split second but it made my speaker just go in a frenzy of static and jumping over my table because the gain is absurdly high so with only 5 volts it's perfectly stable. but still has a huge amount of useless static in the background.. and my computers volume has to be at like under 5% for it to sound clear it sounds perfect at 4% but I don't like the static that I continuously hear in the background |
Are you 14 years old? Serious.
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No. I just turned 15.
And now I can hear a totally random radio station now when I put a resistor in series with the input wire. and it's clearly audible anyone listen to the radio and hear band aid brand advertisements and some kind of weird music? |
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