Search results

I decided to take the measurements a bit further today. I used the simple FET tester to check the Vgs(off) and Idss, then I put the FET into the circuit on my breadboard. Basically, I found the higher the Vgs(off) and Idss the closer the 2N5457 was to operating in the desired area. 2N5457...

I have two quite old J201’s which I measured. (1) 0.881vdc, 0.553mA (2) 0.856vdc, 0.550mA From what I’ve read these are good values, not sure why yet, but they are bound for the Boogie Monster. Regards Mark

I decided to have a go at measuring Vgs (off) and Idss. I used a power supply that supplied 9.3VDC, the 10M resistor on the source that measured 10.1M, and a 1K resistor on the Gate which measured 996 ohm. I have five 2N5457 JFETs this are Vgs and Idss figures. (1) 0.543V, 1.57mA (2)...

This diagram does confuse me a bit. It is very much like a thermonic valve where lower Vgs means more current flow. If I have 0VDC on the Gate and 0.145VDC on the source I have a Vgs of 0.145VDC. According to the common drain source diagram. I should be seeing 3mA with that Vgs. This doesn’t...

I measured around my JFET today. The gate was 0VDC as you’d imagine, the source was 0.145vdc and the drain was 4.17vdc with the 20K drain resistor. Doing a simple bit of maths, if I am to have VCC/2 on the drain, the Id would have to be 661uA with the 1K source resistor. This means the Vgs...

I love the way you finish your pedals, I’m reading Chuck’s articles at the moment.

Great report, where did you get the real deal J201’s from? I noticed PedalPCB has the small boards to use SMD components but are out of stock. I was listening to the Lemonade Drive and wondered if having the bias off a bit was part of the pedals charm? What did you find. Regards Mark

This is what I was seeing when testing the 2N5457. It doesn’t seem terribly meaningful though. Any thoughts? Regards Mark

Music6000 could you provide a link to this part so I don’t order the wrong part? I hate ordering from Mouser as the postage is expensive. Thanks again to those offering assistance. Regards Mark

But what is your take on the FET in my Lemonade board? PPA isn’t the issue. Regards Mark

I would like to point out that I have used Pedal Parts Australia before and I have found them to be very good to purchase from. I think Music6000 was referring to pop up eBay sellers. The issue here is FET’s. It seems quite a few people have had issues with FETs judging by the links in this...

Thanks I’ll remember that. Regards Mark

I bought the 2N5457 from Pedal Parts Australia. I don’t know where these guys got them from. So are you saying they are duds? Who is a recommended seller? I haven’t read the whole thing yet as it’s a bit long winded. Regards Mark

This is the board, it still has to be cleaned etc. Regards Mark

Well, 7.6K is very close to the stock 6.8K, so that makes sense. I disconnected one side of the pot and the drain resistor is 20K which is quite a bit higher. Here is photo of the 2N5457 in the board. Thanks for your assistance. Regards Mark

Thanks for your link. I did read your article, though if you have greater A/C current flow though the collector resistor, won’t you get a greater voltage drop across the resistor and thus greater amplitude of the signal? Regards Mark

Okay, I removed the resistor and used the 10K pot. It wasn’t even close to being half the rail. I end up using a 100K trim pot and at about 19K (will have to double check) I had half the rail on the drain. I played through the pedal and it was much the same sounding as far as I can remember...

Good call M6000, the VDD is 8.35VDC on the battery that I’m using and the voltage on the drain is 6.97VDC. I do have a 10K pot. I can remove the 6.8K and sub the pot in to determine the correct resistor value. I assume the idea is to have half the rail voltage on the Drain. I will give that a...

What about replacing the BC108 with a Darlington pair transistor or use two BC108’s to make a Darlington pair. This would yield higher current gain. Regards Mark