megaphone circuit using lm324 quad op amp

[Electro-Ghost]

can someone tell me where to find some circuit schematics for a megaphone that uses an eletret condenser mic and one of the following amplifier ic's: lm324 quad op amp with 14 pins, or 742 op amp mini dip ic with 8 pins. and also using no transistors or germanium diodes

 

[Dr.EM]

Op-amps are signal devices, not power devices. Using them for a megaphone, the output would be significantly quieter than your voice at the input! Megaphones frequently use class-C amplification. It is dreadfully distorted, but very efficient and just about clear enough for the application. Search for megaphone/bullhorn schematics. You'll need to source a horn speaker for it too, it might be cheaper to buy one?

 

[Electro-Ghost]

so wat type of ic do i need

 

[Electro-Ghost]

also is there any way to make a variable capacior

 

[Hero999]

one of the following amplifier ic's: lm324 quad op amp with 14 pins, or 742 op amp mini dip ic with 8 pins. and also using no transistors or germanium diodes

Those componants aren't suitable for this application?

Use a TL071 and a TDA7052.

Build a pre-amplifier with the TL071 and an output stage with the TDA7052.

Avoid designing circuits around componants in your junkbox unless you're just doing an experiment or it's an emergancy.


What happend with your LM386 megaphone?

Didn't it work?

If so then I advise you try to get it working before attempting to build a more complex design like this.

 

[HiTech]

What happend with your LM386 megaphone? Didn't it work?

It wasn't a good idea founded on a projekt that had least distraction.

 

[audioguru]

It wasn't a good idea founded on a projekt that had least distraction.

The LM324 has terrible crossover "distraction". Its output transistors operate in class-B to reduce supply current (it is low power) instead of class-AB.

 

[stevez]

Yes, there are ways to make variable capacitors. Explain more about your application and I'll share what I know.

 

[Sig239]

It wasn't a good idea founded on a projekt that had least distraction.

ROFLMAO!! Maybe he should gopu_thelocalradioshack and pick up some more parts

 

[HiTech]

Hey Sig239, you like my sig line eh? I couldn't resist the temptation brought on by gopu_therock's silly reply. So I made it into a sig line!

 

[Electro-Ghost]

the reason i want to make a variable cap is to be able to make a simple ham radio transciever for morse code but every circuit i have seen so far requires components that i cannot get my hands on. the two main things that i keep seing are germainum diode and variable cap neither of which i can get. so if one of u could help me find a circuit for a ham radio that doesnt use a germanium diode and doesnt need that many transistors ( i forgot to mention the radio shack i live near has a very limited variety of them too) or diodes and if it does require some diodes and transistors plz supply me with a list of possible substitutes btw if it helps i now have a lm 386 available to me.

 

[Electro-Ghost]

Those componants aren't suitable for this application?

Use a TL071 and a TDA7052.

Build a pre-amplifier with the TL071 and an output stage with the TDA7052.

Avoid designing circuits around componants in your junkbox unless you're just doing an experiment or it's an emergancy.


What happend with your LM386 megaphone?

Didn't it work?

If so then I advise you try to get it working before attempting to build a more complex design like this.

it worked i just broke the mic accidentally

 

[HiTech]

the reason i want to make a variable cap is to be able to make a simple ham radio transciever for morse code but every circuit i have seen so far requires components that i cannot get my hands on. the two main things that i keep seing are germainum diode and variable cap neither of which i can get.

Can you post a link or .bmp of the receiver's schematic? I'd like to see this curcuit you are working on. There are lots of ham radio basic receiver schematics on the internet for you to choose from.

 

[audioguru]

I don't think anybody ever made a ham radio transceiver from RadioShack parts before.
Why not buy real electronic parts from a real electronic parts distributor? They have hundreds of germanium diodes and thousands of variable capacitors in stock, all with detailed spec's.

 

[Electro-Ghost]

here i wanna build something like this i misspoke it is a cw transceiver
**broken link removed**

 

[HiTech]

yeah that's pretty basic! Why not try building from a kit like the ones offered by MFJ? They make some decent stuff and it actually has some worthwhile specs. as well.