Making beeps with only & only transistors no i.c.

[rajaram04]

Hello sir ,
Too many circuits are observed here & on too many sites for beeping circuit using diffrent i.c. Now i want the the same beeping sounds with transistors only . A ll that i need the designing without using any i.c. here but with same results , its a very diffrent case here as no one helped me outside the net world , all i got from here & hope again for the same
Thankssssss

 

[tpetar]

Can you describe "beep" ?

Single tone/freq with short duration ?



See this example :

https://www.mybestnotes.co.in/circuits/mike-beeper.php

The circuit is very simple. It has an RC combination and an UJT (Unijunction Transistor). The speaker is at the output of the UJT. When the circuit is turned on the capacitor C1 starts charging via R1. After a certain level of charging of C1 the input of the UJT i.e. Gate is high enough to turn on the UJT and then as the resistance of the UJT gets low. The capacitor discharges rapidly via the UJT channel. Again when it is fully discharged, the UJT gets in to cutoff mode because the Gate voltage is nearly zero. Then the capacitor again charges via R1. The process repeated and oscillation goes on. One triangular wave in audio frequency range is generating at the output causing the Beep tone.

 

[rajaram04]

sir its amajing what you have explained here thanks
would you please tell me any equivalent substitute for the UJT which can be easily available anywhere?

is there any possiblities with simple NPN & PNP transistors like BC547 BC 557 ?
If yes please have me the proper circuit diagram or any link to it

thanks a lot once again

 

[tpetar]

You can try with 2N2646 similar circuit :

 

[rajaram04]

Re: Making beeps with only & only transistors no i.c.

okk sir i ve one i ll try is there any option for BC547 OR BC 557 for the smae work ?

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is it possible that a UJT can be used as an electronic potentiometer ? please tell thanks

 

[tpetar]

You can also use 2N4891,...

 

[rajaram04]

okk sir & what about the NPN & PNP transistorized circuits ?

 

[tpetar]

Everything is possible why not even with IC like NE555 or similar.

Try to get UJT from market store.

 

[sky_123]

The 555 costs just a few pennies/cents.
When you said transistor, you didn't specify what type of transistor.
(By the way, these types of posts are not suitable for "Digital Signal Processing", they
are more elementary questions.
If you really really do want to do it with just BJTs, then there was a URL pointed out to you
many many times, with purely transistor circuits.
If you go to this link
and just CTRL-F and search for the word "tone", you'll find a "capacitor tester" which makes
tones. It is clear that if you insert a capacitor, then you have got a tone generator.
It uses only transistors and no i.c., and drives a speaker. Then, if you clicked at the
link near the top of the page to go to this page then
you can type CTRL-F again, search for "tone" and you'll find and other tone circuit which makes siren sounds.
Again just using transistors.
I think 99.9% of the circuits you ask for are on those two web pages.

Furthermore, when you have a 555 as tpetar suggests, you can click at another link near the top of that page and
find 50 555 circuits
and search for "tone" by doing CTRL-F again.....

 

[ALERTLINKS]

There are DC buzzers with built in circuit used mostly on pcb for alarm sound. There are some good piezo speakers in cell phones that have nice out put. And work great at 2 KHz resonant frequency. Nice and loud.

If you can find a three terminalunit like used in cheap old telephones, it is driven by a simple one transistor citcuit. The third terminal is for feedback.

 

[godfreyl]

If you go to this link....

Thanks Sky, what a wonderful collection!