How to increase the volume of a metronome?

Greetings,

Comments are sought on additional circuitry to increase the speaker volume of the circuit shown between the lines. Comments on circuit simplifications are also sought. (Maybe a 555 with a couple of pots is as simple as it gets sometimes?)

The Tempo1/Tempo2 resistor pair signifies a pot as does the Vol1/Vol2 pair. Is there a better way to capture pots with LTSpice?

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Thank you,

--
Don Kuenz KB7RPU 

Nations are destroyed, or flourish, in proportion as the poetry, 
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Reply to
Don Kuenz
Loading thread data ...

I'm not going to look at your schematic because the first answer is "just follow it with an audio amplifier", the second answer is "and a speaker that can handle the power", and your answer to that is "I don't want to buy that much speaker".

I'd build a sounder that bangs a tin can with a solenoid. Should give you a healthy "thump".

--
Tim Wescott 
Control systems, embedded software and circuit design 
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Reply to
Tim Wescott

Get a "knocker" out of a "classic" pinball machine. Drive the coil from a suitably adjustable timebase (whether that's an astable multivibrator or an XTAL controlled oscillator/divider is your implementation choice). Adjust the "volume" by threading a screw into the striker plate and increasing/decreasing the "throw" to limit the amount of energy imparted to the striker.

[This can be a really REALLY loud *thump* if so desired -- or, throttled back to be a more abbreviated "tick".]

Downside is it won't be battery powered! :-/

Reply to
Don Y

You can't drive an 8 ohm speaker from the emitter of a 2N3904 like that

- it only has a low output impedance for small signals, and the drive current available is not symmetric.

Either use a small impedance matching transformer in the collector lead (like 2k-8 ohms maybe) with a 0.1uF cap in parallel with the primary, or use the 555 output to drive a proper complimentary BJT pair power driver. Or just use a small audio output driver IC to drive the speaker, like the LM386 - the output automatically biases to around half the single supply and you can block it from the speaker with an appropriately-sized cap.

Reply to
bitrex

Your newsreader has mangled the file by taking out the linefeeds -- I was going to take a second look, but I'd have to slave over it to reconstitute.

At any rate, from experience: you want lots of high frequency content to get a "tick" instead of a "thump". If you're using a speaker this means delivering a very narrow impulse to the speaker, and using a speaker that has good high-frequency characteristics. Fortunately, it also means that you don't need an amplifier in the classic sense -- you can have a simple one-transistor "pull it down hard and let go" amplifier, or a slightly less simple class B pair, and don't worry about crossover distortion.

I'd handle volume either by changing the final stage final voltage, or by modulating the length of the (very narrow!) pulse I send to the final stage. The second method will change the frequency content -- as it gets louder it'll be more of a "thud" than a "tick", but try it, you might like it.

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Tim Wescott 
Wescott Design Services 
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Reply to
Tim Wescott

Speakers are not a problem. There's plenty of high quality speakers available in my bone pile.

My problem is solenoids. Although there's plenty of solenoid coils in the bone pile, there's nary a solenoid en total. :(

At any rate, a solenoid's the way to go. Because it also "warms up" the timbre.

Thank you,

--
Don Kuenz KB7RPU 

Music above all, and for this 
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Reply to
Don Kuenz

The battery was always iffy from the get go. While the wall wart just bided its time.

A pinball "knocker"'s the answer. It provides a warm timbre in a handy little package. Unfortunately it's likely to be the most expensive part of my metronome by far, now that it's "rare."

There were pinball machines at my local dump for the taking a couple of years ago. But trash apparently ripens into rare treasure. Now there's "No Scavenging!" signage plastered all over the place.

Thank you,

--
Don Kuenz KB7RPU 

The man that hath no music in himself, 
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Reply to
Don Kuenz

The canonical response is LM386.

It is not sensible to drive a speaker with a follower here, it will eat your battery in no time, and the speaker does not like the DC bias on it.

--

-TV
Reply to
Tauno Voipio

Tim Wescott wrote:

Let's see if linefeeds "Windows style" works this time:

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Version 4^M SHEET 1 960 936^M WIRE -384 96 -512 96^M WIRE -288 96 -384 96^M WIRE 64 96 -288 96^M WIRE 112 96 64 96^M WIRE 304 96 112 96^M WIRE 112 112 112 96^M WIRE -384 128 -384 96^M WIRE -288 192 -288 96^M WIRE -240 192 -288 192^M WIRE 112 192 112 176^M WIRE 112 192 -16 192^M WIRE 112 224 112 192^M WIRE -384 256 -384 208^M WIRE -240 256 -384 256^M WIRE 16 256 -16 256^M WIRE -384 304 -384 256^M WIRE -240 320 -320 320^M WIRE 176 320 -16 320^M WIRE 176 336 176 320^M WIRE 304 368 304 96^M WIRE -240 384 -288 384^M WIRE 64 384 64 96^M WIRE 64 384 -16 384^M WIRE 240 416 176 416^M WIRE -384 448 -384 384^M WIRE -320 448 -320 320^M WIRE -320 448 -384 448^M WIRE 16 448 16 256^M WIRE 16 448 -320 448^M WIRE -512 464 -512 96^M WIRE -384 480 -384 448^M WIRE -288 480 -288 384^M WIRE 304 496 304 464^M WIRE 176 512 176 496^M WIRE -512 592 -512 544^M WIRE -384 592 -384 544^M WIRE -384 592 -512 592^M WIRE -288 592 -288 544^M WIRE -288 592 -384 592^M WIRE 304 592 304 576^M WIRE -512 640 -512 592^M FLAG -512 640 0^M FLAG 112 224 0^M FLAG 176 512 0^M FLAG 304 592 0^M SYMBOL Misc\\NE555 -128 288 M0^M SYMATTR InstName U1^M SYMBOL res -368 112 M0^M SYMATTR InstName Tempo1^M SYMATTR Value 125k^M SYMBOL res -368 288 M0^M WINDOW 0 36 43 Left 2^M WINDOW 3 49 74 Left 2^M SYMATTR InstName Tempo2^M SYMATTR Value 125k^M SYMBOL cap -368 480 M0^M WINDOW 0 -23 6 Left 2^M WINDOW 3 -41 58 Left 2^M SYMATTR InstName C2^M SYMATTR Value 2.2\xb5F^M SYMBOL res 160 320 R0^M WINDOW 0 -92 42 Left 2^M WINDOW 3 -88 69 Left 2^M SYMATTR InstName Vol1^M SYMATTR Value 500^M SYMBOL Misc\\battery -512 448 R0^M WINDOW 0 12 95 Left 2^M WINDOW 3 17 9 Left 2^M WINDOW 123 0 0 Left 2^M WINDOW 39 0 0 Left 2^M SYMATTR InstName V1^M SYMATTR Value 9^M SYMBOL cap -304 480 R0^M SYMATTR InstName C3^M SYMATTR Value 0.1nF^M SYMBOL cap 96 112 R0^M SYMATTR InstName C4^M SYMATTR Value 100\xb5F^M SYMBOL res 160 400 R0^M WINDOW 0 -86 47 Left 2^M WINDOW 3 -87 76 Left 2^M SYMATTR InstName Vol2^M SYMATTR Value 500^M SYMBOL npn 240 368 R0^M SYMATTR InstName Q1^M SYMATTR Value 2N3904^M SYMBOL res 288 480 R0^M SYMATTR InstName Speaker^M SYMATTR Value 8^M TEXT -392 616 Right 2 !.tran 1 uic^M TEXT -8 176 Left 2 ;1^M TEXT -8 240 Left 2 ;2^M TEXT -8 304 Left 2 ;3^M TEXT -8 360 Left 2 ;4^M TEXT -296 368 Left 2 ;5^M TEXT -296 304 Left 2 ;6^M TEXT -296 240 Left 2 ;7^M TEXT -296 176 Left 2 ;8^M

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Thank you,

--
Don Kuenz KB7RPU
Reply to
Don Kuenz

Good call! You just exterminated the battery eater in my subconscience.

Thank you,

--
Don Kuenz KB7RPU
Reply to
Don Kuenz

The LM386 looks like a winner to me, provided that Tim's "narrow pulse" makes the timbre sound warm enough.

Thank you,

--
Don Kuenz KB7RPU
Reply to
Don Kuenz

Rim shot circuit!

Reply to
bitrex

use a stronger transistor, eg TIP31, 2N3055, etc. a 4 ohm speaker. and increase the supply voltage to 12V

a capacitor in series with pin3 and a diode up from ground will save much energy. maybe start with 100nF and increase it if that's too quiet.

if that's still not enough, you'll want a real audio amplifier... (actually you probably want a real audio amp as it is).

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Reply to
Jasen Betts

Don Kuenz wrote:

The LM386 connected to Realistic Minimus 0.3 Bookshelf Speaker [1] sounds excellent. Although the tempo pot works "as is" my goal is to fine tune the pot / C1 circuitry to 40 bpm in fully counterclockwise position and 208 bpm fully clockwise position.

My latest LTSpice circuit is included after the Note. It pulls in two additional LTSpice subcircuits.

The first subcircuit models an LM386. [2] To use the LM386 just unzip it then drop the lm386.asy and LM386.lib files into the folder with the asc file included after Note.

The second subcircuit models a loudspeaker. [3] To use it just unzip it then drop the Midrange.asc, Tweeter.asc, Wolfer.asc, and Loudspeaker.lib into the folder with the asc file. Another goal of mine is to remove the explicit declaration of Loudspeaker.lib from the asc file.

Note.

  1. formatting link
  2. formatting link
  3. formatting link

------------------------------------------------------------------------ Version 4^M SHEET 1 960 936^M WIRE -384 96 -512 96^M WIRE -288 96 -384 96^M WIRE 64 96 -288 96^M WIRE 112 96 64 96^M WIRE 512 96 112 96^M WIRE 112 112 112 96^M WIRE -384 128 -384 96^M WIRE -288 192 -288 96^M WIRE -240 192 -288 192^M WIRE 112 192 112 176^M WIRE 112 192 -16 192^M WIRE 112 224 112 192^M WIRE -384 256 -384 208^M WIRE -240 256 -384 256^M WIRE 16 256 -16 256^M WIRE -384 304 -384 256^M WIRE -240 320 -320 320^M WIRE 176 320 -16 320^M WIRE 176 336 176 320^M WIRE -240 384 -288 384^M WIRE 64 384 64 96^M WIRE 64 384 -16 384^M WIRE 352 384 320 384^M WIRE 224 416 176 416^M WIRE 352 416 288 416^M WIRE 512 416 512 96^M WIRE 512 416 480 416^M WIRE -384 448 -384 384^M WIRE -320 448 -320 320^M WIRE -320 448 -384 448^M WIRE 16 448 16 256^M WIRE 16 448 -320 448^M WIRE 320 448 320 384^M WIRE 352 448 320 448^M WIRE 512 448 480 448^M WIRE 544 448 512 448^M WIRE 720 448 608 448^M WIRE -512 464 -512 96^M WIRE -384 480 -384 448^M WIRE -288 480 -288 384^M WIRE 176 512 176 496^M WIRE 320 512 320 448^M WIRE 512 576 512 448^M WIRE -512 592 -512 544^M WIRE -384 592 -384 544^M WIRE -384 592 -512 592^M WIRE -288 592 -288 544^M WIRE -288 592 -384 592^M WIRE 720 624 720 448^M WIRE -512 640 -512 592^M WIRE 512 672 512 640^M WIRE 512 768 512 752^M WIRE 720 768 720 720^M FLAG -512 640 0^M FLAG 112 224 0^M FLAG 176 512 0^M FLAG 320 512 0^M FLAG 512 768 0^M FLAG 720 768 0^M SYMBOL Misc\\NE555 -128 288 M0^M SYMATTR InstName U1^M SYMBOL res -368 112 M0^M SYMATTR InstName Tempo1^M SYMATTR Value 125k^M SYMBOL res -368 288 M0^M WINDOW 0 36 43 Left 2^M WINDOW 3 49 74 Left 2^M SYMATTR InstName Tempo2^M SYMATTR Value 125k^M SYMBOL res 160 320 R0^M WINDOW 0 -92 42 Left 2^M WINDOW 3 -88 69 Left 2^M SYMATTR InstName Vol1^M SYMATTR Value 500^M SYMBOL Misc\\battery -512 448 R0^M WINDOW 0 12 95 Left 2^M WINDOW 3 17 9 Left 2^M WINDOW 123 0 0 Left 2^M WINDOW 39 0 0 Left 2^M SYMATTR InstName V1^M SYMATTR Value 9^M SYMBOL cap -304 480 R0^M SYMATTR InstName C2^M SYMATTR Value 0.1nF^M SYMBOL res 160 400 R0^M WINDOW 0 -86 47 Left 2^M WINDOW 3 -87 76 Left 2^M SYMATTR InstName Vol2^M SYMATTR Value 500^M SYMBOL lm386 416 400 R0^M SYMATTR InstName U2^M SYMBOL polcap 96 112 R0^M SYMATTR InstName C3^M SYMATTR Value 100\xc2\xb5F^M SYMATTR SpiceLine Rser=1^M SYMBOL polcap 544 464 R270^M WINDOW 0 32 32 VTop 2^M WINDOW 3 0 32 VBottom 2^M SYMATTR InstName C4^M SYMATTR Value 250\xc2\xb5F^M SYMATTR SpiceLine Rser=1^M SYMBOL polcap -400 480 R0^M SYMATTR InstName C1^M SYMATTR Value 2.2\xc2\xb5F^M SYMBOL polcap 496 576 R0^M SYMATTR InstName C5^M SYMATTR Value 0.05\xc2\xb5F^M SYMBOL res 496 656 R0^M SYMATTR InstName R1^M SYMATTR Value 10^M SYMBOL Woofer 720 672 R0^M WINDOW 38 -32 28 Right 2^M SYMATTR SpiceModel IB3858^M SYMATTR InstName U3^M SYMBOL polcap 224 432 R270^M WINDOW 0 32 32 VTop 2^M WINDOW 3 0 32 VBottom 2^M SYMATTR InstName C6^M SYMATTR Value 10\xc2\xb5F^M TEXT -392 616 Right 2 !.tran 10 uic^M TEXT -8 176 Left 2 ;1^M TEXT -8 240 Left 2 ;2^M TEXT -8 304 Left 2 ;3^M TEXT -8 360 Left 2 ;4^M TEXT -296 368 Left 2 ;5^M TEXT -296 304 Left 2 ;6^M TEXT -296 240 Left 2 ;7^M TEXT -296 176 Left 2 ;8^M TEXT 80 848 Left 2 !.lib Loudspeaker.lib^M

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Thank you,

--
Don Kuenz KB7RPU
Reply to
Don Kuenz

Thanks for the feedback.

Where did you get the symbols and models for LM386 and speaker?

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Tauno Voipio OH2UG
Reply to
Tauno Voipio

The LM386 is available in zipped format at:

formatting link

The loudspeaker is available in zipped format at:

formatting link

My asc shown above contains one error. C1 is really 22 uF and not the

2.2 uF shown. As an aside, it turns out that 2.2 uF works better to debug the circuit because it's easier to see the resultant waveform on my scope.

Thank you,

--
Don Kuenz KB7RPU
Reply to
Don Kuenz

Your asc won't run at all on this machine, no idea why.

NT

Reply to
tabbypurr

This zip file ought to contain everything you need:

formatting link

Thank you,

--
Don Kuenz KB7RPU
Reply to
Don Kuenz

Cheers, works nicely.

Your output voltages are lousy compared to the 9v supply.

Replacing the 386 and using a transistor output would get you much better s wing. But of course it requires other changes to avoid feeding the speaker dc or only operating on one of the 555's transitions. There are a few possi ble ways to do that. You also don't need the zobel if you're just switching it and using no nfb.

Harmonics help with volume. You might inject some at each opportunity, eg o utput of 555 then again with passives across the speaker. Low duty cycle th ere should help with power requirements.

If you go with added digital logic to process the 555 output into a rising edge at each 555 transition you might add some ringing there. The speaker h ousing can also be thin and somewhat resonant.

I'm assuming you don't need to go to BTL or higher psu voltage.

NT

Reply to
tabbypurr

You gave me lots of food for thought. The metronome was originally conceived to be DIY quick and dirty. Your post may motivate me to try harder.

Sharing this project has been a learning experience for me in many ways. In the future, for example, my web server will host all .asc files. The "standalone" nature of a usenet post appealed to me, but it's fraught with too many ?Windows? gotchas.

My original circuit used a transistor, a 2N3904. But it outputted too low of a volume, ergo this thread. FWIW, my metronome with a transistor is available here:

formatting link

Thank you,

--
Don Kuenz KB7RPU
Reply to
Don Kuenz

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