SHO Problem
Information
- Posts: 8
- Joined: 12 Apr 2013, 17:00
Hi All,
I am a newbie here and have not worked with schematics for a long time. So i decided to build SHO since schematic looks quite easy. I took veroboard layout and schematic from here https://hotbottles.wordpress.com/2012/0 ... m-scratch/
The only difference is I used IRF510 instead of BS170.
I build it and it works ok. But then I decided to measure voltage at the MOSFET and it reads
D to ground- ~7.5V
G to ground - ~0.7V
S to ground- ~1.7V
And it is very strange I know it should be something about D -8V,G-3Vand S-1V respectively. But anyway how it even works with gate having lower voltage than source?
Any ideas?
Thanks,
Alex.
I am a newbie here and have not worked with schematics for a long time. So i decided to build SHO since schematic looks quite easy. I took veroboard layout and schematic from here https://hotbottles.wordpress.com/2012/0 ... m-scratch/
The only difference is I used IRF510 instead of BS170.
I build it and it works ok. But then I decided to measure voltage at the MOSFET and it reads
D to ground- ~7.5V
G to ground - ~0.7V
S to ground- ~1.7V
And it is very strange I know it should be something about D -8V,G-3Vand S-1V respectively. But anyway how it even works with gate having lower voltage than source?
Any ideas?
Thanks,
Alex.
Information
- Posts: 8
- Joined: 12 Apr 2013, 17:00
Hi Duckman,
Thanks for the tip. And I actually used the search before posted my problem. But I found nothing related to the issue I have.
Thanks.
Alex.
Thanks for the tip. And I actually used the search before posted my problem. But I found nothing related to the issue I have.
Thanks.
Alex.
Information
- Posts: 8
- Joined: 12 Apr 2013, 17:00
I guess I found the problem. There is nothing wrong with the schematic. I just can't measure voltage at the gate with the ordinary multimeter because I use 10M resistors. Basically in this case multimeter gives me wrong readings.
EDIT: Just checked multimeter specs, it has 1M input impedance. When measuring gate voltage I basically put 1M resistor in parallel with the 10M gate to ground resistor which moves the bias. I simulated it in LTSpice and got the same results as from multimeter.
EDIT: Just checked multimeter specs, it has 1M input impedance. When measuring gate voltage I basically put 1M resistor in parallel with the 10M gate to ground resistor which moves the bias. I simulated it in LTSpice and got the same results as from multimeter.
Information
- Posts: 8
- Joined: 12 Apr 2013, 17:00
Thanks for suggestions. In fact my schematic worked in a first place. I was just concerned about multimeter's readings. But now that solved.