2N3055 heat sink

alec_t said:

If you want an up-down swept frequency instead of the nee-naw siren sound you could try this circuit :-
View attachment 118873
U1a and U1b create a large amplitude slow up-down ramp which modulates the frequency of a sawtooth tone generated by U1c. (Without D1 the duty cycle, rather than the frequency, would be modulated).
Inputs of the three unused gates of the CD40106 package should be grounded.

I've attached a siren.wav file of the sound it generates. (Delete the .txt extension). Also attached is the LTspice simulation file.

Click to expand...

What is U1a U1b U1c ?

They are three CMOS Schmitt trigger inverters The CD40106 IC contains six such inverters.

alec_t said:

They are three CMOS Schmitt trigger inverters The CD40106 IC contains six such inverters.

Click to expand...

I clicked link and read information. I don't understand how to solder it into a circuit to make it work. Sound like it is automatic when it receives a sin wave in there is a square wave out. I don't see how that is useful 555 makes a square wave out. Looks like the package has 6 triggers 1-2, 3-4, 5-6, 8-9, 10-11, 12-13. Explain how this works?

audioguru said:

A relay wears out. Also its coil produces a high flyback voltage which would destroy the 555 driving it.
Simply mix the outputs of the sound producing 555s with 2 resistors feeding the 2N3055 then use the switching 555 to reset (pin 4) one of them and a transistor inverter to alternately reset the other one.

Your 2N3055 is a DC amplifier and will not work properly with an input coupling capacitor. Also you are feeding its base with such a high voltage that its base-emitter reverse maximum allowed voltage of -7V is exceeded which damages it.

How can you filter the squarewave buzzing that sounds like an acid rock overdriven electric guitar?

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Yes relay will wear out but I won't be using it much it should last a long time. Not sure what you mean about resetting pin 4. I removed cap on base of 2N3055. Here is a simpler circuit all relay needs to do is switch back and forth from 2 resistors on the same 555 to make Hz go low, high, low, high, 1KHz to 1.5KHz then back to 1KHz over and over. I did not do the math I only put 5K on R5 so how how it works. I connected relay to 555 #1 as long as output is 50% duty cycle relay is ON 50% for the time then OFF 50% of the time.

gary350 said:

Explain how this works?

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A CD40106 inverter has two signal input voltage thresholds; one above and one below about half the supply voltage. (The difference is called 'hysteresis'). Let's assume the supply voltage is 5V. The thresholds will typically be about 4V and 3V. If the signal input (whether a sinewave or not) goes above 4V the output goes low (0V). If the signal then goes lower the output stays low until the input goes below 3V and at that point the output goes high (5V). The output voltage can be used to charge a capacitor via a resistor, and the voltage developed across the capacitor can be fed back as the input signal. The result is an oscillator, with the output snapping between high and low, i.e a square-wave.
As for wiring this IC, the +ve supply voltage goes to pin 14 and the ground (0V) connection is pin 7. It is advisable to use a 14-pin socket for the IC if you are unused to soldering ICs. Bear in mind that CMOS circuits are static-sensitive, so don't go dancing around in nylon knickers on synthetic carpet before handling them .

I can Open the .txt file or I can Copy it then Save it as a Text file.
But How do I delete its .txt extension so that I can hear the Wave file in it?

Your recent schematic has problems:

audioguru said:

How do I delete its .txt extension so that I can hear the Wave file in it?

Click to expand...

Download the file. Right-click on the file name and use the Rename option in the pop-up.
And yes, it sounds awful. But aren't sirens meant to?

gary350 said:

relay will wear out but

Click to expand...

When #1 output is low then 6.8k. When #1 output is high then 6.8k//68k.
I did not try it!

Thanks Alec.
I downloaded siren.wav.txt in Windows 10 and it calls it a Text Document that I cannot change. Its name is already Siren.wav.

ronsimpson said:

When #1 output is low then 6.8k. When #1 output is high then 6.8k//68k.
I did not try it!
View attachment 118885

Click to expand...

Duty cycle on 555 #1 is 50.2%

Duty cycle is 73% for 555 #2 using R4=6.6K and R6 = 4K

I only have to change 3 resistors to test this an see how it sounds.

This is the finished circuit. Duty cycle is 50.2% for 555 #1.

audioguru said:

I downloaded siren.wav.txt in Windows 10 and it calls it a Text Document that I cannot change. Its name is already Siren.wav.

Click to expand...

Ignore Windows moaning about files being unworkable if you change the extension. It isn't really a text file (I only added the .txt extension to the name so that this forum's software would allow the upload). The Rename option lets you simply delete ".txt" and save the file as Siren.wav

ronsimpson said:

When #1 output is low then 6.8k. When #1 output is high then 6.8k//68k.
I did not try it!
View attachment 118885

Click to expand...

I built this it sounds better with a square wave 53% duty cycle but it still sounds weird. I guess I need to connect output to scope to look at it. It sounds like output KHz stays the same and volume goes up and down. I think it will sound better if output changes from 1K to 1.5K. I changed C1 to .3uf it sounds better.

I made a small circuit change because it is not good to have relay switch between 2 different resistors. The circuit will probably make a disconnect reconnect sound every time the relay changes directions. I put a 4K resistor and 2.7K resistor in series to get 6.7K. Relay will short out the 2.7K resistor causing the R value to changes from 4K to 6.7K every time relay changes direction and the circuit never loose the connection. First half if the circuit is finished and tested. Relay goes on/off just like it should 50% on and 50% off using a .3uf cap for C1. I found a 2.8K resistor that tests 2.75K so I am a tiny bit off 50 ohms.

The board is finished but second half of the circuit does not run. 555 #1 runs so I removed it and put 555 #2 in its place and it runs. Now I know both 555s work. I ohm out all 8 pins of the IC socket to make sure them connect from front to back and solder connected are good to all the resistors, caps, ground, and + connection. Combined resistance of R3 R4 R5 are correct. With battery connected no sound comes out of the speaker. If I put R7 and the speaker on the 555 circuit I built last week with the 12v batteries it works even if I swap out the 555 on this board that is not working. I swapped out C2 also. Every things ohms good and tests good but it does not work. Only thing I have not done is replace variable resistors with fixed resistors. Only reason I used these variable resistors it was quick and easy to dial in the exact resistance I need and not spend 2 hrs search for fixed resistors and soldering several fixed resistors together to get close as possible to the value I need. I can not find any reason for the circuit to not work. 555 #1 is not connected to 555 #2 yet. I can remove 555 #1 and 555 #2 still not work. Ohm meter shows nothing is shorted and all connections are good. I used online calculator to get the resistor values maybe it is wrong. Maybe the green color capacitor should be orange? Now that I think of it online 555 calculator resistor values are not even close to TTL book resistors values that might be a good place to start tomorrow.

Of course your oscillator does not work, it uses the wrong 555.

Your photo of 555 #2 is broken up but it sure looks like it IS NOT a ordinary high current NE555 or LM555.
Instead it looks like it is a low current Cmos version TLC555 (the C is for Cmos).

You are looking at an antique TTL book that never heard of a modern Cmos 555 and your "Circuit Calculator" also is very old.
You should be looking at the datasheets.

audioguru said:

Of course your oscillator does not work, it uses the wrong 555.

Your photo of 555 #2 is broken up but it sure looks like it IS NOT a ordinary high current NE555 or LM555.
Instead it looks like it is a low current Cmos version TLC555 (the C is for Cmos).

You are looking at an antique TTL book that never heard of a modern Cmos 555 and your "Circuit Calculator" also is very old.
You should be looking at the datasheets.

Click to expand...

Number on IC is NE555P 20ma?

These 2 NE555P were working good on the TTL book siren circuit board with this 100 ohm resistor and the same 8 ohm speaker.

I moved the 2 NE555P to the other circuit board along with the 100 ohm resistor and same 8 ohm speaker and it does not work? Only things that is actually different is duty cycle is much closer to 50% online calculator says 53% for 1KHz and 55% for 1.5KHz. 555 #1 = 50.2% duty cycle.

This morning first thing I did was change the 8 ohm speaker to this tiny little micro watt speaker and "WOW" the circuit works excellent. I could not have guessed better 1KHz & 1.5KHz sound perfect. LOL. Timer on relay is perfect. Nothing wrong with circuit problem was the stupid operator. LOL. Wow I am impressed how much better this siren sounds compared to the original TTL book circuit, it sounds exactly like the European sirens I hear on TV. OK time to add the 2N3055 transistor. I assume if pin 3 output is above 7v 2N3055 transistor will clip. Output at speaker with the speaker as load = 6.2 volts. Output with no speaker load = 6.2v. Both tests with 40 ohm resistor. Now that rain has stopped I will do a test with car battery.

Your new circuit board with the clearer photo shows an NE555P for the timer and an AC NE555P for the oscillator.
You also show a new 0.1uF capacitor.
Maybe the 555 from Malaysia is really a Cmos one?

Your new micro speaker looks like a piezo transducer that has an impedance that is much higher than 8 ohms and even a Cmos 555 can easily drive it.
A Cmos 555 might have trouble driving the 100 ohms feeding a 2N3055.

It works but not loud. Connected to car battery I am not sure it is louder than the AA batteries they produce 2 amps. Output to 3w speaker sounds about like 1w. I think it needs a transistor preamp between the 555 & 2N3055. The only transistors I have are 2N3904 & 2N2222. Maybe a 5w or 10w audio amp IC will be better I don't know the number for any of them.?