Dumb question about "matched transistors"

[Deperduci]

have you inserted them the right way? also being smd, might have been better tolerances.. or a wire that should be going to to the gate and drain swappedon the board?

 

[Kroars]

I've heard people mention from time to time about needing "matched quad set" of transistors for certain builds.

I just ordered the XC Phase board and it calls for 4x 2N5952's, do these "need" to be matched for this build?
What happens if they aren't matched?

Also, what spec am I matching?

TIA!!

Just in case:

2N5951 Quad Set - GuitarPCB

N-channel Jfet 2N5951 Quad Set - Hand Matched - Genuine Tested.

guitarpcb.com

They are out of stock now, but he often updates his stock. I believe I have two sets coming to me, should be delivered in a week or less. I only need one set now, so if you want to send me a message I’d happily send you a set if you need for the cost I bought them for.

Happy building!

 

[MichaelW]

Just in case:

2N5951 Quad Set - GuitarPCB

N-channel Jfet 2N5951 Quad Set - Hand Matched - Genuine Tested.

guitarpcb.com

They are out of stock now, but he often updates his stock. I believe I have two sets coming to me, should be delivered in a week or less. I only need one set now, so if you want to send me a message I’d happily send you a set if you need for the cost I bought them for.

Happy building!

Yah, there's a couple places that is selling matched sets, most are out of stock. I'm pretty well loaded up on MMBF5457's, I think I'll try to get my JFet Matcher working right and find a matched set out of my inventory.

 

[MichaelW]

have you inserted them the right way? also being smd, might have been better tolerances.. or a wire that should be going to to the gate and drain swappedon the board?

I think I've tried them. The board clearly makes DSG spots and I matched those. I haven't spent too much time trying to troubleshoot. But I guess now's as good a time as any I had to order 3 boards from Oshpark. I'm going to try to build out another one.

 

[BryGuy]

I might try these from Aion since I don’t have much of a stash of jfets to sort currently.

2SK208-GR, matched set for phasers

This is a matched set of 2SK208-GR JFETs for use in phasers such as the BOSS PH-1r, pre-soldered to adapter boards for through-hole applications.

aionfx.com

 

[spi]

I use the ROG technique to measure my jfets.

A closer look at the Fetzer Valve

 

[Coda]

I use the ROG technique to measure my jfets.

A closer look at the Fetzer Valve

Yep. Works good.

 

[fig]

I have a couple JFet Matcher boards from RullyWow. I've built one of them so far but it doesn't seem to work. Everything I've stuck in there measures 4.35v. So unless my WHOLE stash of JFETS are actually extremely closely matched and I could retire selling them as matched sets or my borked the build somehow. I'm going to try building it again with some of the spares I got.

I use the ROG technique to measure my jfets.

A closer look at the Fetzer Valve

I believe that’s what the jFET Matcher Michael has is based on, though there are a few versions (improved, greatly improved, cheetah-supreme). It’s not too deep of math and was fun to work out once, but the online calc is killer. I now use a Peak thingy and it does everything but solder the little bugger for me.

 

[jimilee]

Tagboard has some great jfet matcher circuits.

 

[Chuck D. Bones]

It's not enough that they are matched. Vgs,off needs to be in the correct range for the phaser to work. 2N5457 has a HUGE Vgs,off range and the ones at the high end won't work. The Vgs,off range for 2N5952 is -1.3V to -3.5V. If you sub other part numbers, make sure the ones you pick have a Vgs,off in that range, preferably near the middle of the range.

 

[fig]

It's not enough that they are matched. Vgs,off needs to be in the correct range for the phaser to work. 2N5457 has a HUGE Vgs,off range and the ones at the high end won't work. The Vgs,off range for 2N5952 is -1.3V to -3.5V. If you sub other part numbers, make sure the ones you pick have a Vgs,off in that range, preferably near the middle of the range.

Remember those 2N5248s? I still have all of those matched quads. I never did try any in the Phase 90, but I will now!

 

[Chuck D. Bones]

I think you mean 2N5246. Good option. Pick ones with the higher Vgs,off.

 

[fig]

I think you mean 2N5246. Good option. Pick ones with the higher Vgs,off.

I came back to correct myself and here you've taken care of me. Will do

 

[MichaelW]

It's not enough that they are matched. Vgs,off needs to be in the correct range for the phaser to work. 2N5457 has a HUGE Vgs,off range and the ones at the high end won't work. The Vgs,off range for 2N5952 is -1.3V to -3.5V. If you sub other part numbers, make sure the ones you pick have a Vgs,off in that range, preferably near the middle of the range.

Hey @Chuck D. Bones, I've managed to come up with 4 matched MMBF5457's but they're a bit higher than your suggested range.
-1.19, -1.19, -1.19, -1.34

Think these will work in a Phase 90?

I've got a crap ton more MMBF547's but they're not mounted on adapters. Got a suggestion on how to test those little suckers?
I can't get my micro clips to stay on the legs.

I suppose to could mount a dozen of them and see if I get any better ones....

 

[MichaelW]

Ok, I made a little jig to test SMD JFETs...

I pulled 10 MMBF5457's and unfortunately none of them were close. VGs off measured in the -.5-.7 range on all 10.

I wonder if its because they were MMBF5457LT1's. I'm not completely sure what the LT1 designation denotes.

 

[MichaelW]

Broke down and bought a matched quad from Barry, he had them on sale.

I'm planning to socket and test them against my matched set of 5457's as well as some random J201's.

 

[swyse]

Broke down and bought a matched quad from Barry, he had them on sale.

I'm planning to socket and test them against my matched set of 5457's as well as some random J201's.

I'm interested to see the results of your experimenting, I'd like to build a phaser at some point but am not excited about matching jfets.

 

[MichaelW]

I'm interested to see the results of your experimenting, I'd like to build a phaser at some point but am not excited about matching jfets.

I'll update this thread when I get to building. But you can build the Phase II and skip all this crap

 

[MichaelW]

have you inserted them the right way? also being smd, might have been better tolerances.. or a wire that should be going to to the gate and drain swappedon the board?

Incidentally, I'm an idiot, I did have them in the wrong way . There was nothing wrong with the first matcher I built.

 

[Deperduci]

Incidentally, I'm an idiot, I did have them in the wrong way . There was nothing wrong with the first matcher I built.

cool, I'm going try to build that on perfboard, got a small stack of mounted 5457's I hope I can find a pair for to make a 45, and I agree find a mu-tron LED based phaser if you don't want the QA dance finding sets