Resistor To Ground - What is the purpose?

PreCD · 21st July 2012, 02:08 PM

In the picture attached you will find a resistor to ground and another section with a capacitor/resistor to ground. What is the purpose for this type circuitry?

MagicBox · 21st July 2012, 02:11 PM

With the two diodes above it, it forms a voltage reference, referenced against the upper supply rail, resulting in Vsupply - 2x diode drop.

BV · 21st July 2012, 02:19 PM

R-C: Boucherot cell

PreCD · 21st July 2012, 02:34 PM

Thanks gentlemen.

jan.didden · 21st July 2012, 02:35 PM

Without R621 there would be no current through the diodes and they would just sit there rather stupid

jan didden

PChi · 21st July 2012, 02:36 PM

I agree with BV. An alternative name is Zobel (not sure of the spelling) network.

I believe that it ensure that the output stage is loaded by a low impedance that helps to control the high frequency gain of the output stage so helps to maintain stability.
Another reason that I have read is that it partly compensates for the inductive part of a typical loudspeaker load.

PreCD · 21st July 2012, 02:42 PM

Could I also refer to the R-C combo in my schematic as a snubber?

Nico Ras · 21st July 2012, 08:47 PM

A snubber is used to snub or quench a transient or arc. They are normally used across a switching element and a current will shunt through it as the switch starts opening (not closing) so that an arc will not form across the contacts.

A zobel is a network that if placed at the input of a filter network and if looking into the filter, it appears as a constant impedance over a wide frequency range.

Boscoe · 21st July 2012, 08:52 PM

The RC combo is there to help reduce DC offset is it not? The cap is high impedance at low frequencies lowering the gain?

dadod · 21st July 2012, 08:58 PM

This RC is Zobel at output.

21st July 2012, 02:11 PM	#2
MagicBox diyAudio Member Join Date: Sep 2011	With the two diodes above it, it forms a voltage reference, referenced against the upper supply rail, resulting in Vsupply - 2x diode drop. __________________ Negative Feedback: The Need for Speed

21st July 2012, 02:35 PM	#5
jan.didden diyAudio Member Join Date: May 2002 Location: Great City of Turnhout, Belgium Blog Entries: 6	Without R621 there would be no current through the diodes and they would just sit there rather stupid jan didden __________________ /Yes! Its out: Linear Audio Vol 5! I'm not an "accademic", just a plodder who loves a challenge - Ian Hegglun

21st July 2012, 08:47 PM	#8
Nico Ras diyAudio Member Join Date: Nov 2005 Location: Amanzimtoti - East Coast of South Africa	A snubber is used to snub or quench a transient or arc. They are normally used across a switching element and a current will shunt through it as the switch starts opening (not closing) so that an arc will not form across the contacts. A zobel is a network that if placed at the input of a filter network and if looking into the filter, it appears as a constant impedance over a wide frequency range. __________________ Kindest regards Nico

21st July 2012, 08:52 PM	#9
Boscoe diyAudio Member Join Date: Feb 2010 Location: England	The RC combo is there to help reduce DC offset is it not? The cap is high impedance at low frequencies lowering the gain? __________________ I thought about it once, but then thought again.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

21st July 2012, 02:19 PM	#3
BV diyAudio Member Join Date: Sep 2005 Location: Trnava, Slovakia	R-C: Boucherot cell

21st July 2012, 02:34 PM	#4
PreCD diyAudio Member Join Date: Sep 2011 Location: USA	Thanks gentlemen.

21st July 2012, 02:36 PM	#6
PChi diyAudio Member Join Date: Jan 2012 Location: Staines, UK	I agree with BV. An alternative name is Zobel (not sure of the spelling) network. I believe that it ensure that the output stage is loaded by a low impedance that helps to control the high frequency gain of the output stage so helps to maintain stability. Another reason that I have read is that it partly compensates for the inductive part of a typical loudspeaker load.

21st July 2012, 02:42 PM	#7
PreCD diyAudio Member Join Date: Sep 2011 Location: USA	Could I also refer to the R-C combo in my schematic as a snubber?

21st July 2012, 08:58 PM	#10
dadod diyAudio Member Join Date: Apr 2006 Location: Zagreb	This RC is Zobel at output.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
purpose and value importance of resistor	CoolJazz	Tubes / Valves	15	12th April 2012 05:26 PM
Purpose of series input resistor in guitar preamp?	miallen	Solid State	14	17th December 2010 10:42 AM
a resistor to ground?	lanchile07	Chip Amps	11	23rd November 2007 02:16 PM
Parallel LM3886, input ground, power ground, safety resistor and oscillations.	markiemrboo	Chip Amps	5	9th August 2007 03:50 PM
general purpose relay to mute/ground outputs	mazurek	Parts	1	27th February 2006 02:29 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read