From - Mon Oct 23 08:38:33 2000 Path: nntp1-sf.pbi.net!cyclone-sf.pbi.net!206.141.251.3!nntp0.riverside.il.ameritech.net!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!tank.news.pipex.net!pipex!tube.news.pipex.net!pipex!not-for-mail From: Terry Pinnell Newsgroups: sci.electronics.misc Subject: Re: Chirping Crickets Date: Mon, 23 Oct 2000 13:35:21 +0100 Organization: UUNET WorldCom server (post doesn't reflect views of UUNET WorldCom Lines: 95 Message-ID: References: <39F265F4.5B3EB40B@physics.ucsd.edu> Reply-To: terrypin@dial.pipex.com NNTP-Posting-Host: userdw80.uk.uudial.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Trace: lure.pipex.net 972304544 23520 62.188.8.74 (23 Oct 2000 12:35:45 GMT) X-Complaints-To: abuse@uk.uu.net NNTP-Posting-Date: 23 Oct 2000 12:35:45 GMT X-Newsreader: Forte Agent 1.7/32.534 Xref: cyclone-sf.pbi.net sci.electronics.misc:54373 Daniel Queen wrote: >What is the best way to make a chirping noise. (with electronics of >course) I am trying to make a cricket sound effect for halloween. Daniel: One of the following two circuits might be suitable. They were originally published by Elektor magazine, but that was around two decades ago, so I'm sure the company won't mind my reproducing them. The first one is particularly simple: 5 resistors, 3 capacitors, a transistor, diode and a 4049. I've attached scans of both schematics with a copy of this post in alt.binaries.schematics.electronic. Alternatively, let me know if you'd like me to e-mail them to you. Terry Pinnell Hobbyist, West Sussex, UK ================================= (1)'Cricket'; originally by J. Schmitz, then included in Elektor's book '300 Circuits' in 1979. "Miniaturisation of electronic components and the increasing use of ICs has now reached the stage where quite interesting circuits can be fitted inside a match-box. This particular circuit simulates the chirping of a cricket, and in spite of its ultra-low power output it should have a useful range of about 10 ft. In the immediate vicinity of the 'insect' the chirping sound meets hi-fi standards - in the sense that it is true to the original. The circuit uses 6 CMOS inverters and a typical NPN transistor. The inverters are used in three astable multivibrators (AMVs). The N3/N4 AMV modulates a further AMV, consisting of N3 and N6. The interaction of these two AMVs produces the chirping sound. A third multivibrator (Nl/N2) switches the chirping on and off periodically, thus determining the rest periods. The square-wave output from N5 is fed to buffer-stage T1. This transistor drives the 'loudspeaker', which is actually a hgh-impedance dynamic microphone. The Senheiser type HM35 is a good (and cheep - sorry, cheap) choice, but many other types will also do quite well. The current consumption is very low, so the miniature mercury batteries should have a very long life. Open-heart surgery to replace the batteries should be necessary only very infrequently. A PCB [shown in original source] is available." ================================= (2) 'Cricket Simulator'; originally in Jul/Aug '83 issue of Elektor. "This simulator gives a faithful reproduction of the chirping of a cricket. The circuit comprises four oscillators of which the first, N1, produces the basic high note. The frequency of this note is set by potentiometer P1 such that it lies within the resonant range of the crystal buzzer: the tone is then loudest. To obtain the typical chirping noise, the 4 kHz square wave output of N1 is amplitude modulated by a frequency of 10...20 Hz. This frequency is produced by oscillator N2 and the modulation takes place in digital frequency changer N4. To make the end result realistic, the 'cricket' must, of course, not chirp continuously but with suitable pauses. This is effected by oscillator N7/N8 and frequency changer N6. The oscillator output has a duty cycle ratio which is directly proportional to the ratio of the two sections of potentiometer P4, and can therefore be changed as desired. The duration of the total oscillator cycle is about 30 seconds, but because of tolerances this can vary appreciably. If the pauses cannot be set long enough, C4 should be replaced by a larger value. The initial adjustment to the circuit is that of P1 to achieve the basic tone. For this the buzzer must be connected directly to the output of gate N1 (pin 3 of IC1). The buzzer is then connected to pin 11 of IC1 and P2 is adjusted to obtain the typical chirping tone of a cricket. Next, connect the buzzer to pin 3 of IC1 and adjust P3 so that the chirping noise is heard three to six times per second, according to taste. Finally, connect the buzzer to the output of the simulator and the (artificial) cricket is ready for use. Depending upon the value of C4 and the setting of P4, it may take a little while before the cricket emits its first chirp. As the current consumption of the circuit is only about 1 mA, the cricket can chirp away quite happily for a long while on a 9 V battery."