[sdiy] Re: Source of 2N5459 FETs

[Steven Downhill]

Hi Oren,

>Hi Steven and all,

>You can probably ditch the JFETs all together and use JFET input op amps 
>as non-inverting buffers, too.
>This would have been an expensive luxury back in 1974.

>HTH,
>Oren

You've lost me with this comment! (my electronics knowledge is limited at
the moment).
How would you go about doing this?.

Regards
Steven

-----Original Message-----
From: Oren Leavitt [mailto:oleavitt at ix.netcom.com] 
Sent: 19 March 2004 04:33
To: Synth DIY (synth-diy at dropmix.xs4all.nl)
Subject: Re: [sdiy] Re: Source of 2N5459 FETs


Hi Steven and all,

You can probably ditch the JFETs all together and use JFET input op amps 
as non-inverting buffers, too.
This would have been an expensive luxury back in 1974.

HTH,
Oren

Steven Downhill wrote:

>>Hi,
>>The FET's in that circuit are the selected ( orange) ones. 2n5459's have a
>>    
>>
>wide
>  
>
>>spec on pinch-off voltage. The orange ones are selected for a pinch-off of
>>    
>>
>5V or
>  
>
>>less, the yellow coded ones are the rejects. the 2n4392's will work well
in
>>    
>>
>the
>  
>
>>4035 circuit as their pinch-off voltage is always less than 5V.
>>    
>>
>
>Thanks for the additional info.
>Now that I know the above I've decided to go with the 2N4392s (I can get
>these immediately for half the price of the 2N5459s and use them in some
>other projects).
>
>  
>
>>The VCO I am referring to is the standard 4027-1 circuit used in 2600's .
>>    
>>
>Same
>  
>
>>circuit was used in Axxe and later Ody's.
>>    
>>
>
>I've looked at this schematic before and always wondered what the FETs were
>as they're just labelled with (I assume) ARP's own part number.
>
>I would love to be able to build my own ARP Odyssey or 2600 at some point
in
>the future.
>Do you think that this could be done using the schematics / service manuals
>from the Net and finding equivalent semiconductors to those which are now
>obsolete?.
>
>Regards
>Steven
>
>-----Original Message-----
>From: Dana Scott [mailto:danas at egosys.com] 
>Sent: 18 March 2004 11:50
>To: Steven Downhill
>Cc: synth-diy at dropmix.xs4all.nl
>Subject: Re: [sdiy] Re: Source of 2N5459 FETs
>
>
>Hi,
>The FET's in that circuit are the selected ( orange) ones. 2n5459's have a
>wide
>spec on pinch-off voltage. The orange ones are selected for a pinch-off of
>5V or
>less, the yellow coded ones are the rejects. the 2n4392's will work well in
>the
>4035 circuit as their pinch-off voltage is always less than 5V.
>The VCO I am referring to is the standard 4027-1 circuit used in 2600's .
>Same
>circuit was used in Axxe and later Ody's.
>-Dana
>
>----- Original Message ----- 
>From: "Steven Downhill" <Steven.Downhill at brother.co.uk>
>To: "'Dana Scott'" <
>Cc: <synth-diy at dropmix.xs4all.nl>
>Sent: Thursday, March 18, 2004 4:21 AM
>Subject: RE: [sdiy] Re: Source of 2N5459 FETs
>
>
>  
>
>>Hi Dana,
>>
>>    
>>
>>>What are you building? If you are building ARP VCO circuit, you will have
>>>      
>>>
>>better
>>    
>>
>>>luck using a 2n4392. It does come  in a metal can instead of a plastic,
>>>      
>>>
>>tho'.
>>    
>>
>>>-Dana
>>>      
>>>
>>The plan was to use them in the ARP 4035 VCF (assuming the below schematic
>>is OK).
>>
>>http://www.arptech.synth.net/pdf/4035.pdf
>>
>>Thanks for the info on the ARP VCO.
>>Which version of it are you referring to?.
>>
>>Regards
>>Steven
>>
>>-----Original Message-----
>>From: Dana Scott
>>Sent: 17 March 2004 17:45
>>To: Steven Downhill; synth-diy at dropmix.xs4all.nl
>>Subject: Re: [sdiy] Re: Source of 2N5459 FETs
>>
>>
>>What are you building? If you are building ARP VCO circuit, you will have
>>better
>>luck using a 2n4392. It does come  in a metal can instead of a plastic,
>>tho'.
>>-Dana
>>
>>----- Original Message ----- 
>>From: "Steven Downhill" <Steven.Downhill at brother.co.uk>
>>To: <synth-diy at dropmix.xs4all.nl>
>>Sent: Wednesday, March 17, 2004 9:31 AM
>>Subject: [sdiy] Re: Source of 2N5459 FETs
>>
>>
>>    
>>
>>>Hi All,
>>>
>>>Does anybody know of a company in the UK with the exception of RS that I
>>>      
>>>
>>can
>>    
>>
>>>obtain 2N5459 FETs from?.
>>>(RS seem the only company to have this part and they'll be out of stock
>>>      
>>>
>>for
>>    
>>
>>>the next 10 weeks!).
>>>
>>>Equivalent part suggestions are also welcome.
>>>
>>>Thanks.
>>>
>>>Regards
>>>Steven
>>>      
>>>
>
>
>
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-- 
Oren Leavitt
oleavitt at ix.netcom.com




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