[sdiy] discrete/no-OTA VCO

[Jim Palmer]

no offense, but man that's an ugly baby...


Jim Patchell wrote:
> 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
>>
>> --------------------------------------------
>> check out various dan music at:
>>
>> http://www.myspace.com/lossnyc 
>>
>> http://www.soundclick.com/lossnyc.htm
>>
>>
>> http://www.indie911.com/dan-snazelle
>> (or for techno) http://www.myspace.com/snazelle
>>
>>
>>
>>> 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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>>>>
>>>> Harry Bissell & Nora Abdullah 4eva
>>>>
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