[sdiy] discrete/no-OTA VCO

[Jim Patchell]

He..he...

Here are pictures of the VCO.....

http://www.noniandjim.com/Jim/FirstSynth/vco.jpg
http://www.noniandjim.com/Jim/FirstSynth/vcorear.jpg

-Jim


Dan Snazelle wrote:
> I am a bit confused as I have the Linear Applications Handbook VOL one from 1977 and the only triangle VCO is lm3900 based.
> Do i have the wrong volume?
> 
> I want to get more of these books so any info would be great!
> 
> thanks
> 
> 
> 
> also...TOny...is there an APP note number for the mentioned circuit?
> 
> thanks
> 
> --------------------------------------------
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> http://www.soundclick.com/lossnyc.htm
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> 
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> 
>> Date: Mon, 29 Dec 2008 16:51:59 -0500
>> From: tony at makenoisemusic.com
>> To: harrybissell at wowway.com
>> Subject: Re: [sdiy] discrete/no-OTA VCO
>> CC: synth-diy at dropmix.xs4all.nl
>>
>> harrybissell at wowway.com wrote:
>>> There is a triangle wave VCO that uses two opamps and one
>>> transistor. The CV is input to the first opamp (an inverting
>>> integrator) through two resistors, one to inverting and one to non-inverting.
>>> A transistor shunts the non-inverting side to ground. Unequal
>>> resistors make the ramps equal in time. The other opamp is a schmitt
>>> trigger.
>>>
>>> Classic circuit suffers from relatively small tuning range (maybe 10-20:1)
>>> because eventually the control voltage must get really large to get the
>>> current in.  Current controlled oscillators have much wider range.
>>>
>>> I think this is in the National Semiconductor Linear Apps databook...
>>> but I can't find it right now.
>>>
>>>   
>> It is in that databook. I designed a variation of this circuit into a 
>> small noise instrument I built for somebody. They work great for sound 
>> design and noise, but definitely are not able to be tuned to 1V/oct or 
>> any standard that I recognized.
>>
>> TOny
>>
>>> H^) harry
>>>
>>>
>>>
>>> On Mon, 29 Dec 2008 08:45:02 -0500, DAF wrote
>>>   
>>>> thanks for all of the suggestions thus far - I am particularly 
>>>> intrigued by the UJT voltage-controlled relaxation osc. especially 
>>>> because of the low parts count, but I am wondering if the UJT is 
>>>> also going the way of the dodo bird, and also is the control of 
>>>> frequency linear over a wide enough range (I see it used in synths 
>>>> that use octave divider schemes)?
>>>>
>>>> In that Ray Wilson schematic, he says for a VCLFO, leave out the 
>>>> parts in RED; are you to join the resulting gaps together on the 
>>>> wires shown remaining?
>>>>
>>>> Dave
>>>>
>>>> ----- Original Message ----- 
>>>> From: "Simon Brouwer" 
>>>> To: "sdiy" 
>>>> Sent: Monday, December 29, 2008 3:13 AM
>>>> Subject: Re: [sdiy] discrete/no-OTA VCO
>>>>
>>>>     
>>>>> Here is one:
>>>>>
>>>>> http://www.elby-designs.com/asm-2/lfo/lfo1-asm2-cct.pdf
>>>>>
>>>>>
>>>>> DAF schreef:
>>>>>       
>>>>>> Hello - can someone point me to a circuit for a  voltage-controlled
>>>>>> lfo that uses discrete or other easy to source parts.  I have used an
>>>>>> OTA-based design in the past, but I want to design around more generic
>>>>>> parts.  I seem to remember a vco that used a discrete JFET?  I don't
>>>>>> neet expo response or temp compensation.  I am looking for about a 2
>>>>>> to 10 Hz response range.  I don't want to use any specialty chips or
>>>>>> OTA's, just discrete transistors and op-amps.   Any help greatly
>>>>>> appreciated.
>>>>>>
>>>>>> thanks,
>>>>>> Dave
>>>>>>         
>>>>> -- 
>>>>> Vriendelijke groet,
>>>>> Simon Brouwer.
>>>>>
>>>>> | http://nl.openoffice.org | http://www.opentaal.org |
>>>>>
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