Gyrator Question

athos56 · 7th May 2009, 11:22 PM

I wired up a gyrator and put in my 40v supply, it ended up with 4 volts at the output, I assume I miss wired it, however just to be sure I'm going to ask a quick question. I used this schematic
http://www.loetstelle.net/projekte/gyrator/gyrator.php
Do I hook this up between B+ and ground, or along the B+ rail like a normal choke?

Iain McNeill · 7th May 2009, 11:48 PM

Not speaking Dutch my guess is it's an in-line device. It's polarity sensitive so you gotta connect it the right way X1-1 to the +ve rail X1-2 to the load.

Also. it needs a current through it to work. Were you testing open circuit?

As you pull current through it, the cap charges up and "programs" the current source Q1-R3. The MOSFET regulates it's Rds to maintain said current.

Wavebourn · 7th May 2009, 11:53 PM

Right. And a voltage drop on it will be about 5V plus voltage drop on the resistor in source.
There was a thread recently about gyrators.

Here it is: http://www.diyaudio.com/forums/showt...15#post1778215

athos56 · 7th May 2009, 11:54 PM

Ok, I read something that led me to believe it went the other way, I'll try it again, hopefully I didn't fry it

Hearinspace · 8th May 2009, 03:49 AM

Quote:

There was a thread recently about gyrators.

Hi Wavebourn,
Why does the term Gyrator apply to your circuit? It's your original idea, why not give it an original name?
Thanks

ErikdeBest · 8th May 2009, 09:07 AM

Hi Athos56

It is indeed a directional device: you should connect X1-1 to the B+, and X1-2 to the following cap in the PS circuit. In other words, X1-1 should be more positive (higher voltage) than X1-2.

The text is German, actually!

Erik

whitelabrat · 8th May 2009, 03:37 PM

I tried to build that gyrator myself and promptly smoked it. I haven't tried to repair it yet, but I believe my mistake was to work exclusively from the schematic. I'd suggest using the PCB layout as a wiring guide.

My test was done on a 300v +180ma circuit. Indeed X1-1 in your "In" and X1-2 is your "Out". The next test I'll do will be on a lower voltage/current circuit with a resistor load. Won't get a chance to play until after I get into my next house.

Pictures? I'm curious how you've done yours.

ErikdeBest · 8th May 2009, 05:41 PM

I have seen someone else complaining about the circuit, in that it oscillated wildly...maybe that also happened to Whitelabrat's circuit?

I have made a layout to build this unit on protoboard, but was not able to put it together, yet. I included space for a small resistor (couple R) in series with the drain as well as space for a gate stopper resistor (around 1k). I think that at least the gate-stopper is very important!

Let's see if I can put it together in the weekend and test it.

athos56 · 8th May 2009, 05:52 PM

Well, so I tested my amp for the first time and got distorted output of music, removing the Gyrator will be my first troubleshooting measure.

whitelabrat · 8th May 2009, 07:07 PM

Could be that I didn't smoke it at all. I didn't think about oscillation. It sure sounded like that is what it was doing. It was almost as if it were amplifying the B+ noise instead of filtering it.

7th May 2009, 11:22 PM	#1
athos56 diyAudio Member Join Date: May 2006 Location: Yakima, Washington	Gyrator Question I wired up a gyrator and put in my 40v supply, it ended up with 4 volts at the output, I assume I miss wired it, however just to be sure I'm going to ask a quick question. I used this schematic http://www.loetstelle.net/projekte/gyrator/gyrator.php Do I hook this up between B+ and ground, or along the B+ rail like a normal choke?

7th May 2009, 11:53 PM	#3
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	Right. And a voltage drop on it will be about 5V plus voltage drop on the resistor in source. There was a thread recently about gyrators. Here it is: http://www.diyaudio.com/forums/showt...15#post1778215 __________________ If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative.

8th May 2009, 09:07 AM	#6
ErikdeBest mostly thinkerer diyAudio Member Join Date: Mar 2003 Location: Maputo - Mozambique	Hi Athos56 It is indeed a directional device: you should connect X1-1 to the B+, and X1-2 to the following cap in the PS circuit. In other words, X1-1 should be more positive (higher voltage) than X1-2. The text is German, actually! Erik __________________ my surname is indeed 'de Best': neither misspelling nor snobbism! Ask SY!

8th May 2009, 05:41 PM	#8
ErikdeBest mostly thinkerer diyAudio Member Join Date: Mar 2003 Location: Maputo - Mozambique	I have seen someone else complaining about the circuit, in that it oscillated wildly...maybe that also happened to Whitelabrat's circuit? I have made a layout to build this unit on protoboard, but was not able to put it together, yet. I included space for a small resistor (couple R) in series with the drain as well as space for a gate stopper resistor (around 1k). I think that at least the gate-stopper is very important! Let's see if I can put it together in the weekend and test it. __________________ my surname is indeed 'de Best': neither misspelling nor snobbism! Ask SY!

8th May 2009, 05:52 PM	#9
athos56 diyAudio Member Join Date: May 2006 Location: Yakima, Washington	Failure Well, so I tested my amp for the first time and got distorted output of music, removing the Gyrator will be my first troubleshooting measure.


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7th May 2009, 11:48 PM	#2
Iain McNeill diyAudio Moderator Emeritus Join Date: Oct 2007 Location: Santa Cruz, California	Not speaking Dutch my guess is it's an in-line device. It's polarity sensitive so you gotta connect it the right way X1-1 to the +ve rail X1-2 to the load. Also. it needs a current through it to work. Were you testing open circuit? As you pull current through it, the cap charges up and "programs" the current source Q1-R3. The MOSFET regulates it's Rds to maintain said current.

7th May 2009, 11:54 PM	#4
athos56 diyAudio Member Join Date: May 2006 Location: Yakima, Washington	Ok, I read something that led me to believe it went the other way, I'll try it again, hopefully I didn't fry it

8th May 2009, 03:37 PM	#7
whitelabrat diyAudio Member Join Date: Dec 2006 Location: Maryland	I tried to build that gyrator myself and promptly smoked it. I haven't tried to repair it yet, but I believe my mistake was to work exclusively from the schematic. I'd suggest using the PCB layout as a wiring guide. My test was done on a 300v +180ma circuit. Indeed X1-1 in your "In" and X1-2 is your "Out". The next test I'll do will be on a lower voltage/current circuit with a resistor load. Won't get a chance to play until after I get into my next house. Pictures? I'm curious how you've done yours.

8th May 2009, 07:07 PM	#10
whitelabrat diyAudio Member Join Date: Dec 2006 Location: Maryland	Could be that I didn't smoke it at all. I didn't think about oscillation. It sure sounded like that is what it was doing. It was almost as if it were amplifying the B+ noise instead of filtering it.

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