Author Topic: Scullcom function generator - component functions ?  (Read 713 times)

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Offline netdudeukTopic starter

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Scullcom function generator - component functions ?
« on: May 05, 2019, 08:29:56 am »
Hi

What is the purpose of C21 and R33 ?

Thanks
 

Online oPossum

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Re: Scullcom function generator - component functions ?
« Reply #1 on: May 05, 2019, 09:35:48 am »
Reduce noise from the power supply getting in to the output.
 
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Offline bd139

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Re: Scullcom function generator - component functions ?
« Reply #2 on: May 05, 2019, 09:47:42 am »
C21 is a decoupling capacitor. It reduces the impedance at AC on the junction of R33 and R15 therefore establishing a stable voltage there. The amplifier looks like a summing amplifier so this reduces the “wiggle” on the DC offset input at DC and allows AC to float on that DC level. At DC the capacitor is effectively open.

You can model this by drawing the circuit twice. Once with the capacitor shorted (at DC) and once when it’s open (at AC) and think about each case independently.
« Last Edit: May 05, 2019, 09:49:50 am by bd139 »
 
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Offline netdudeukTopic starter

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Re: Scullcom function generator - component functions ?
« Reply #3 on: May 05, 2019, 09:14:16 pm »
Thanks guys.
 


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