I was hoping to make a beep sounds like the Price is Right giant spin wheel. Beeps fast during the spin and slows down as it loses momentum. Are there any pre-existing designs for something like this? Thanks.

 

I would be using a 555 astable oscillator, or pieze buzzer, and use a reed switch contact and magnets on the wheel,

Or microswitch and pins on the wheel as it passes the switch, when the switch closes it pulses the astable.

 

I was hoping to make a beep sounds like the Price is Right giant spin wheel. Beeps fast during the spin and slows down as it loses momentum. Are there any pre-existing designs for something like this? Thanks.

A possibility is one of the numerous electronic roulette wheel kits, but I don't know how many of them have realistic decay.

The one I found was probably either Maplin or Velleman, whatever it was had a OTP PIC - you can bet your life they set the security bit so you can't read it and burn modified code on a flash part.

Some kits may already have the sound effect required, but its as simple as sensing current in the common line for the LEDs.

 

I was hoping to make a beep sounds like the Price is Right giant spin wheel. Beeps fast during the spin and slows down as it loses momentum. Are there any pre-existing designs for something like this? Thanks.

What is the "wheel" that you are using?

 

Here is what I would do.

Here are parts url's
http://www.ebay.com/itm/10pcs-10W-R...166973?hash=item282e851afd:g:0SwAAOSwol5Yy1Ur
http://www.ebay.com/itm/2Pcs-12-9-5...380166?hash=item3f6dff3006:g:y1oAAOSwo4pYEcKY
Best of luck
A.H.W.

 

Wow, thank you for the recommendations! I will try the reed switch.

 

What could you use to amplify the buzzer sound? This will be at a fair so there will probably be loud background noise.

Will I need to get a relay and larger speakers?

Sorry for the noob questions.

 

What could you use to amplify the buzzer sound? This will be at a fair so there will probably be loud background noise.

Will I need to get a relay and larger speakers?

Sorry for the noob questions.

You can get piezo sounders with built in electronics - the Sonalert is one of the best known and probably as loud as you need.

There's an off the shelf type for fire alarms - not far off hearing damage!!!

 

What could you use to amplify the buzzer sound? This will be at a fair so there will probably be loud background noise.

Will I need to get a relay and larger speakers?

Sorry for the noob questions.

As @ian field said just get a better buzzer. Make sure it is a Continuous tone buzzer & that the reed switch can handle the current.
A.H.W.

 

Small piezo beepers that are self-oscillating usually have a one-transistor oscillator circuit built in with the piezo element acting as a resonant crystal. Depending on the make and model, the oscillator can take a noticeable amount of time to start, and might not make full loudness beeps when the wheel is spinning quickly. Probably not a problem, but something to watch out for.

ak

 

Summer is here again. I didn't make this circuit last year but will this year.

I had a question. If the reed switch lands near the magnet on the pinwheel, won't the beeper continue to have one long continuous beep? Is there a way to limit the beep even if it closes/activates the reed switch?

 

If the reed switch lands near the magnet on the pinwheel, won't the beeper continue to have one long continuous beep?

Yes.

Is there a way to limit the beep even if it closes/activates the reed switch?

Yes. But it isn't as simple as a battery-switch-beeper circuit.

What you are describing is having a constant beep time that is short enough for when the wheel is spinning, but shuts off after a fixed time interval even if the wheel stops with one of the magnets sitting on top of a switch. The circuit is called a monostable, short for monostable multivibrator. A 555 circuit (LMC555 is better for battery operation) can do this, and probably drive the beeper directly. You should get plenty of volume with a 12 V battery or power source. How comfortable are you with assembling a small circuit, either on perf board or using a solderless prototyping board?

There are many ways to do this kind of timing circuit. With this simple circuit, the beeper might sound continuously at high wheel speeds, with individual beeps becoming distinguishable at medium and slow speeds. This is a consequence of the timing capacitor no having enough time between triggers to fully discharge. A counter-based circuit does not have this problem, but is a bit more complex. I think a 555 circuit will work here.

Have you selected a beeper to use? Where are you located?

ak

 

I was going to use a stylophone for more sound options but those dreams went down the drain. I'm comfortable with circuits and soldering. I'm located in Los Angeles.

Yes.

Yes. But it isn't as simple as a battery-switch-beeper circuit.

What you are describing is having a constant beep time that is short enough for when the wheel is spinning, but shuts off after a fixed time interval even if the wheel stops with one of the magnets sitting on top of a switch. The circuit is called a monostable, short for monostable multivibrator. A 555 circuit (LMC555 is better for battery operation) can do this, and probably drive the beeper directly. You should get plenty of volume with a 12 V battery or power source. How comfortable are you with assembling a small circuit, either on perf board or using a solderless prototyping board?

There are many ways to do this kind of timing circuit. With this simple circuit, the beeper might sound continuously at high wheel speeds, with individual beeps becoming distinguishable at medium and slow speeds. This is a consequence of the timing capacitor no having enough time between triggers to fully discharge. A counter-based circuit does not have this problem, but is a bit more complex. I think a 555 circuit will work here.

Have you selected a beeper to use? Where are you located?

ak

 

The sound - an integrated piezo beeper (like what beeps at you in a microwave oven) is the most simple path, but other than buying a dozen different models and trying them, you have very little control over the quality (or even the pitch) of the sound. Next up is something that sounds like what you want, but needs a small amplifier and speaker.

Here is the LMC555 datasheet.

http://www.ti.com/lit/ds/symlink/lmc555.pdf

Read up on it and come back with any questions. Figure 3 on page 8 is the basic one-shot circuit. Because the 555 is not a true monostable, 2 resistors and capacitor are added to the trigger input to prevent the continuous-sound condition you mentioned above. The 555 output can source or sink 200 mA, which should be more than enough for one or more piezo beepers in parallel to be heard above the crowd noise. All of the reed switches are connected in parallel and replace the switch in this schematic.

ak

 

Might modulate one shot so that at stop time is fixed, say 1 sec. and at high speed time will be short.

 

The beep times will be shorter at high speeds naturally, because C1 (above) will not have long enough time to fully discharge. You can increase this effect with a resistor in series with pin 7.

ak

 

Why do you need a 555? It seems like you could just do the following, only requiring the sensor, buzzer, an op amp, mosfet, and some passives. Get an active buzzer. Have it be controlled by a mosfet, being controlled by the hall with comparator or reed switch. Then have that signal also charge a capacitor though a large resistor. The capacitor gets quickly discharged through a low value resistor when the switch is off. If the capacitor gets charged to close to the supply voltage, which should take about a second, it pulls a comparator low, connecting a mosfet to ground.

 

Going even farther, you don't need the opamp. The trick is to AC-couple the switch signal into the MOSFET so it doesn't stay on continuously when a magnet is parked over a switch.

2 resistors
1 capacitor
1 2N7000 MOSFET
1 magnetic reed switch
1 or more beepers

ak

 

Any chance you can hand-hold me and draw the circuit? I can make the circuit, but can't design it - this part is out of my league.

Thanks for all the responses.

 

I think you just have the mosfet switch the active buzzer. BUT, there is a capacitor series with the reed switch controlling the mosfet. This way, it blocks DC (when the switch is continuously on). You would also want a pulldown resistor for the mosfet, which additionally discharges the capacitor.