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Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Jeroen Belleman <jeroen@nospam.please> Newsgroups: sci.electronics.design Subject: Re: Oscillators in LTspice Date: Fri, 18 Oct 2024 19:52:44 +0200 Organization: A noiseless patient Spider Lines: 89 Message-ID: <veu72r$3d5sm$1@dont-email.me> References: <veu2ki$3cmo3$1@dont-email.me> <67128f12$1$2873018$882e4bbb@reader.netnews.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Fri, 18 Oct 2024 19:49:15 +0200 (CEST) Injection-Info: dont-email.me; posting-host="f2caf82bb3ef965e5d700a4e1ca81787"; logging-data="3577750"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19Oi1ZiAf1UfkUBvklsAuzL" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Cancel-Lock: sha1:R6IdQ65GsSiIU8TL8Gf4ZqlCAhQ= In-Reply-To: <67128f12$1$2873018$882e4bbb@reader.netnews.com> Content-Language: en-US Bytes: 3468 On 10/18/24 18:38, bitrex wrote: > On 10/18/2024 12:33 PM, Cursitor Doom wrote: >> Gentlemen, >> >> I've never spiced an oscillator AFAICR. Do they self-start in spice >> simulators (LT in particular)? IOW, did Mike Engleheart build something >> into the engine which generates wideband 'background' noise, particularly >> at 'power up' as it were? I'm assuming there must be some such mechanism >> and if there is, it must be present by default for all schematics one >> attempts to simulate and not just oscillators? > > They can be a PITA to start in LTSpice, like this old chestnut really > doesn't want to run at all IME in LT but is fine on a breadboard: > > <https://upload.wikimedia.org/wikipedia/en/thumb/8/83/Forrest_Mims_hand_drawn_circuit_1983.jpg/220px-Forrest_Mims_hand_drawn_circuit_1983.jpg> I tweaked it a bit, but the simulation below works. Jeroen Belleman Version 4 SHEET 1 1348 680 WIRE 0 -48 -160 -48 WIRE 160 -48 0 -48 WIRE 336 -48 160 -48 WIRE 0 16 0 -48 WIRE 160 16 160 -48 WIRE 336 80 336 -48 WIRE 160 128 160 96 WIRE 272 128 160 128 WIRE -160 176 -160 -48 WIRE 160 176 160 128 WIRE 0 224 0 96 WIRE 64 224 0 224 WIRE 96 224 64 224 WIRE -160 288 -160 256 WIRE 64 304 64 224 WIRE 96 304 64 304 WIRE 208 304 96 304 WIRE 336 304 336 176 WIRE 336 304 272 304 WIRE 384 304 336 304 WIRE 416 304 384 304 WIRE 0 320 0 224 WIRE 336 352 336 304 WIRE 0 464 0 400 WIRE 160 464 160 272 WIRE 336 464 336 432 FLAG 336 464 0 FLAG 160 464 0 FLAG 0 464 0 FLAG -160 288 0 FLAG 384 304 out FLAG 96 304 b SYMBOL npn 96 176 R0 SYMATTR InstName Q1 SYMATTR Value 2N3904 SYMBOL res 144 0 R0 SYMATTR InstName R3 SYMATTR Value 1k SYMBOL pnp 272 176 M180 SYMATTR InstName Q2 SYMATTR Value 2N3906 SYMBOL cap 272 288 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C1 SYMATTR Value 22µ SYMBOL res 320 336 R0 SYMATTR InstName RL SYMATTR Value 30 SYMBOL res -16 304 R0 SYMATTR InstName R2 SYMATTR Value 56k SYMBOL res -16 0 R0 SYMATTR InstName R1 SYMATTR Value 220k SYMBOL voltage -160 160 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value PWL(0 0 1u 9) TEXT -192 400 Left 2 !.tran 10 TEXT -192 448 Left 2 !.ic v(b)=0 TEXT 496 0 Left 2 ;Flasher, according to Forrest Mims. TEXT 496 48 Left 2 ;Jeroen Belleman - 20241018