View Full Version : PIEZO is not very loud using FREQOUT

04-07-2007, 08:24 AM
Help with Freqout - I connected the piezo speaker·to pin 7 on the BS2 and it is not very loud at all.· Any clues?· I have the BS2 in a socket.· My BS1 USB chip is way louder using the SOUND command.· I would assume that the drive from the BS2 was equal or even better than the BS1?· Any one have the same experience?·· Is it related to the way that FREQOUT sends the signal to the Piezo?

Kevin Wood
04-07-2007, 10:16 AM
What frequency are you using for the tone?

Messing around with the WaM kit, I've found that a 1000Hz tone is fairly quiet, while a 3500Hz to 4500Hz tone is considerably louder.

04-07-2007, 10:20 AM
I set my BS2 up earlier today with the speaker lesson in the book and did not think it was working. I changed freq. to 4000 and it was MUCH louder. Then I put it back to 2000 and had to almost cup my ear towards the speaker to hear it.
My hearing is pretty bad but I expected it to be louder than that.

Chris Savage
04-07-2007, 12:51 PM

·· Speakers,·especially Piezo Speakers have what’s called a resonant frequency. The speaker performs best at and around this range of frequencies. I believe the Piezo we carry has a resonant frequency of ~3500 Hz, so frequencies in this area will be louder than all others. Especially difficult to produce would be frequencies outside the frequency range of the speaker. For example, you won’t be producing 20 Hz bass from the Piezo. I hope this helps. Take care.

Chris Savage
Parallax Tech Support

04-07-2007, 08:09 PM
That makes sense Chris, but why would it be louder on the BS1 Sound command than with the Freqout on the BS2 ?
Nellastav made no mention of the freq. used for each stamp. Perhaps they were NOT the same.

04-07-2007, 11:12 PM
>but why would it be louder on the BS1 Sound
>command than with the Freqout on the BS2 ?

Because the 'sound' command produces a squarewave which has the fundamental plus higher harmonics (which the piezo can respond to (it's a tweeter only))
The 'freqout' command produces a sinewave pretty devoid of harmonics.

04-08-2007, 07:39 AM
Thanks for the answers.· I am trying to make a guitar tuner so the frequencies would have to be lower than what the piezo will deliver with a sine wave as was gracously pointed out.· I used the same frequency for both the Sound and the Freqout command 330 HZ.· Trouble with the Sound command is it does not cover the lower audio range needed for the Low E sound that is whay I trued the freqout command with BS2.· I think I will try and tinker with a speaker and a low watt amp and see it Freqout will drive a speaker through an amp.· Anyone know of a post that may describe an amp used with Freqout?