[sdiy] There is no fun analogue chips anymore!

[Dave Manley]

There's a simple EDN reader circuit (somewhere in their archives) that demonstrates this characteristic by making the cap the tunable element in an oscillator.

-Dave

-------- Original Message --------
 From: Barry Klein <Barry.L.Klein at wdc.com>
 Sent: Thu, Jun 28, 2012 01:19 PM
 To: Gordon JC Pearce <gordonjcp at gjcp.net>; sdiy diy	 <synth-diy at dropmix.xs4all.nl>
 CC: 
 Subject: Re: [sdiy] There is no fun analogue chips anymore!

>Many designers don't realize that effective capacitance drops often 50% with DC across multilayer type ceramics - and this varies between manufacturers and voltage ratings.
>I hadn't come across any that got worse over time though.  Any background on this - a particular vendor?
>
>Barry
>
>
>-----Original Message-----
>From: synth-diy-bounces at dropmix.xs4all.nl [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Gordon JC Pearce
>Sent: Thursday, June 28, 2012 12:26 PM
>To: sdiy diy
>Subject: Re: [sdiy] There is no fun analogue chips anymore!
>
>On 28/06/12 20:16, Pete Hartman wrote:
>> So I have displayed my ignorance publicly again :-)
>>
>> Thanks for the pointers.  Glad to see it's not as complicated as I had 
>> thought from some long past exposure to things like "flowing solder 
>> with a toaster oven".
>>
>> Pete
>
>http://www.gjcp.net/~gordonjcp/capacitor.jpg
>
>That was taken with a cheapy USB microscope.  It's an 0.1μF ceramic capacitor in a Kenwood HT, part of the mic preamp, and like all little ceramic caps prone to going leaky if there's a DC voltage across them - like, uh, the preamp bias voltage.  The replacement in the picture was hand-soldered, cleaned up with some flux cleaner, and you'd hardly tell it had been touched.  I used a fairly pointy soldering iron tip and some tweezers that I'd reshaped a little to be better at picking up tiny grain-of-sugar components.  I didn't use the USB microscope because it is too "laggy" to update.
>
>Now, I don't need glasses, but I'm 38 and I can tell my eyesight isn't as sharp as it was ten years ago ;-)
>
>It's not that hard...
>
>--
>Gordonjcp MM0YEQ
>
>
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