Path: 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

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