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</o:shapelayout></xml><![endif]--></head><body lang=FR-CA link=blue vlink=purple><div class=WordSection1><p class=MsoPlainText><b><span lang=EN-CA>>Maybe you loose current through the protection diodes the MAT-02 and <o:p></o:p></span></b></p><p class=MsoPlainText><b><span lang=EN-CA>>LM394 has between emitter and base. (Base of output transistor?)<o:p></o:p></span></b></p><p class=MsoPlainText><b><span lang=EN-CA>>Thats one of the differences to the 2n3904s.<o:p></o:p></span></b></p><p class=MsoPlainText><span lang=EN-CA><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Yes.. VERY possible..<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>I will stick with my 2N3904 matched pair for very low frequencies..<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Unless I find something else.. <o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Thanks !<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA><o:p> </o:p></span></p><p class=MsoPlainText><span lang=FR>-----Message d'origine-----<br>De : Synth-diy [mailto:synth-diy-bounces@synth-diy.org] De la part de René Schmitz<br>Envoyé : 16 janvier 2020 15:56<br>À : synth-diy@synth-diy.org<br>Objet : Re: [sdiy] Working with the ASM1 VCO.. weird MAT-02 behaviour...</span></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>Hi Jean-Pierre,<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>Maybe you loose current through the protection diodes the MAT-02 and <o:p></o:p></p><p class=MsoPlainText>LM394 has between emitter and base. (Base of output transistor?)<o:p></o:p></p><p class=MsoPlainText>Thats one of the differences to the 2n3904s.<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>Best,<o:p></o:p></p><p class=MsoPlainText> René<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>On 16.01.2020 17:48, Jean-Pierre Desrochers wrote:<o:p></o:p></p><p class=MsoPlainText>> Hi list,<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> I'm working on the Elby-Design ASM-1 VCO<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> https://www.elby-designs.com/webtek/asm-1/vco/vco-asm1-cct.pdf<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> Im want to use it as a 1v/oct LFO (.05hz to 20hz)<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> I first mounted the circuit on my protoboard with success.<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> at first I used a matched pair of 2N3904 for Q1A & Q1B<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> instead of the MAT02 shown in the schematic.<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> I could reach very low frequencies (as low as .04hz).<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> But to do so I needed to replace R9(56k) for a 33k temporarily. Fine.<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> This morning I replaced both 2N3904 with a genuine MAT-02<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> and started the same frequency measurements as yesterday.<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> I bumped into something weird..<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> Here are the actual measurements I first did using 2x2N3904:<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> mVolt at 1k TEMPCO resistor vs Sawtooth period<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 158.0mV => 0.050sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 176.0mV => 0.100sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 193.8mV => 0.200sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 212.0mV => 0.400sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 229.8mV => 0.800sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 247.5mV => 1.6sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 265.5mV => 3.2sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 283.2mV => 6.4sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 301.7mV => 12.8sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 319.7mV => 25.6sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> (18mV steps, nice exponential response!)<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> Now here are the actual measurements with a MAT-02:<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> mVolt at 1k TEMPCO resistor vs Sawtooth period<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 157.0mV => 0.050sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 175.0mV => 0.100sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 193.0mV => 0.200sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 211.0mV => 0.400sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 229.0mV => 0.800sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 247.0mV => 1.6sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> 271.0mV => 3.2sec<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> **** Now trying to go further increasing the TEMPCO mVolts*<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> **** the oscillator starts backing up and re-increase its frequencies !!!*<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> **** I could not go further lowering the frequency. *<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> I tried 3 different MAT-02's and even LM394's<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> and they all behave the same.<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> Using different matched pairs of 2N3904 worked perfectly..<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> I suspect MAT-02’s minimum base to emitter current reached (???)<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> What am-I missing here ??<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> By the way, all the IC's I'm using here are genuine one's<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> (TL082, MAT-02, CA3140, LM311).<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> JP<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> _______________________________________________<o:p></o:p></p><p class=MsoPlainText>> Synth-diy mailing list<o:p></o:p></p><p class=MsoPlainText>> Synth-diy@synth-diy.org<o:p></o:p></p><p class=MsoPlainText>> http://synth-diy.org/mailman/listinfo/synth-diy<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>-- <o:p></o:p></p><p class=MsoPlainText>--<o:p></o:p></p><p class=MsoPlainText>synth@schmitzbits.de<o:p></o:p></p><p class=MsoPlainText>http://schmitzbits.de<o:p></o:p></p><p class=MsoPlainText>_______________________________________________<o:p></o:p></p><p class=MsoPlainText>Synth-diy mailing list<o:p></o:p></p><p class=MsoPlainText>Synth-diy@synth-diy.org<o:p></o:p></p><p 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