Article View: sci.electronics
Article #19037Re: the drip
From: William Swan
Date: Thu, 14 Apr 1988 00:55
Date: Thu, 14 Apr 1988 00:55
27 lines
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1519 bytes
In article <1625@sigma.UUCP> I wrote:
>> As for other "joke" circuits... my favorite is still "the drip".
>
>The original "drip" from, I think, the Feb '67 Popular Electronics, used
>a germanium transistor that would periodically emit short bursts of AF...
For those who are interested, here is a pseudo-SPICE listing for the
device as built from available components 19 years ago:
VCC 1 0 1.55V (old Radio Shack "Steel Clad" 15c C cell :-)
R1 1 2 3.3M
R2 2 3 1k
C1 3 0 5uf
L1 1 4 ?speaker (~50-100 ohm? el cheapo)
L2 4 5 448mH
Q1 5 2 6 NPN (germanium?, type unknown)
C2 5 6 .1u
C3 6 0 .22u
D1 6 0 DIODE (1N448 germanium)
With some manipulation of values (esp. reducing C1 and making L2 "real" by
adding series resistance - not shown here) and introduction of a small
"noise" source I've been able to induce SPICE to simulate the circuit
(with silicon devices and a higher supply voltage, as far as I've tested).
--
William Swan {ihnp4,decvax,allegra,...}!uw-beaver!tikal!sigma!bill
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Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!husc6!bloom-beacon!mit-eddie!uw-beaver!tikal!sigma!bill From: bill@sigma.UUCP (William Swan) Newsgroups: sci.electronics Subject: Re: the drip Message-ID: <1634@sigma.UUCP> Date: 14 Apr 88 00:55:10 GMT References: <8287@oberon.USC.EDU> <2763@saturn.ucsc.edu> <1625@sigma.UUCP> Reply-To: bill@sigma.UUCP (William Swan) Organization: Summation Inc, Kirkland WA Lines: 27