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PostPosted: Fri May 19, 2023 11:27 am 
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RESOLVED
I have been using the Lil Orange Phaser as my Go-To phaser circuit for 3 years now. Either they work as intended or I messed up and I suss out the error. This one is different. I have three built pcb's that all present the same issue. I have been populating and assembling in groups of 3 and 4 this last batch, so I did take into consideration that I must've obviously made an error across all 3 pcb's But I checked all of my components, checked the guide and the installed value, and I visually compared to one of my many successful builds. I know it's stressed to use matching quads for the 2N5952 transistors, but I've never gone out of my way with the transistors and never had issue.
What I am experiencing here is a different shift in phase than the expected effect and the trimpot gets the pcb to phase when dialed in at 230 when it should phase at 9/10 oclock. It still works! It's a phaser, but just not the same. It's a mystery for now. Same chips, same everything as the others. I feel there's something I'm overlooking, but perhaps these symptoms and trimmer setting sound familiar and raises an eyebrow to someone that knows. Thanks!


Last edited by RobertJay on Fri May 26, 2023 4:25 am, edited 1 time in total.

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PostPosted: Fri May 19, 2023 12:12 pm 
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New production ON Semi 2N5952 don't work quite right anymore. They "work", but they just don't sound quite right. You'll either need to find NOS Fairchild 2N5952 from a trusted supplier (which is not going to be easy) or you will need to find an alternate JFET. For example, we're currently using 2SK30A in the Classic Phaser kit now, but it has a different pinout, so we had to update the PCB. The Li'l Orange Phaser is out of stock because we need to update the PCB to accept the pinout for the 2SK30A.

You could still use something like the 2SK30A in the current Li'l Orange Phaser PCB. You'd just need to twist the leads a little bit so that they go in the correct eyelets.

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PostPosted: Fri May 19, 2023 5:05 pm 
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byoc wrote:
You could still use something like the 2SK30A in the current Li'l Orange Phaser PCB. You'd just need to twist the leads a little bit so that they go in the correct eyelets.

When you do this, we recommend stripping three short lengths of insulation off some hookup wire and sliding them over the leads of the transistor. That way, when you bend the leads around to match the pinout on the PCB, you won't have to worry about them shorting against each other.

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PostPosted: Mon May 22, 2023 3:57 am 
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Thank you ALL!!! I just ordered a bunch of 2SK30A's. This is a great circuit and the small size lets me use these lil pcbc's in my multi effect builds. I was able to find matched quads and bought a bunch of unchecked ones. What are the characteristics wer are looking for when matching quads? hFE? I think I read it's the voltage between the Base / Emitter? I'm happy to test them all to find suitable quads...


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PostPosted: Mon May 22, 2023 8:49 am 
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byoc wrote:
New production ON Semi 2N5952 don't work quite right anymore. They "work", but they just don't sound quite right. You'll either need to find NOS Fairchild 2N5952 from a trusted supplier (which is not going to be easy) or you will need to find an alternate JFET. For example, we're currently using 2SK30A in the Classic Phaser kit now, but it has a different pinout, so we had to update the PCB. The Li'l Orange Phaser is out of stock because we need to update the PCB to accept the pinout for the 2SK30A.

You could still use something like the 2SK30A in the current Li'l Orange Phaser PCB. You'd just need to twist the leads a little bit so that they go in the correct eyelets.


Someone pointed out the Lil phaser Schematic shows a 220k trimmer but the parts list calls for 100k. Did anything change? I just tested and matched transistors and it made no difference. Looking into that Trimmer, or I must have a rogue component value in there somewhere.


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PostPosted: Mon May 22, 2023 11:50 am 
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RobertJay wrote:
Thank you ALL!!! I just ordered a bunch of 2SK30A's. This is a great circuit and the small size lets me use these lil pcbc's in my multi effect builds. I was able to find matched quads and bought a bunch of unchecked ones. What are the characteristics wer are looking for when matching quads? hFE? I think I read it's the voltage between the Base / Emitter? I'm happy to test them all to find suitable quads...


How are you matching JFETs? It's not something you can do easily with a multimeter. You are trying to match the Vgs(off) or Gate Source Cutoff Voltage. It will likely be in the 1 ~ 1.5V range. This is the voltage at which, when applied to the gate of the JFET, the Source and Drain will have it's least amount of resistance. You want to match this particular spec, because when it's matched, it means that all 4 phase stages will be working together. The more closely matched, the more closely in synch the phase stages will be working together at the exact same time and thus producing a more intense phase effect.

The problem with the new production 2N5952 is that the Vgs(off) MIN/MAX differential is too small. It doesn't matter if you match them. It goes through it's full "sweep" with only half of the LFO cycle, so it creates a sort of squared off saw wave instead of the smooth asymmetrical sine wave that you're expecting from the Phase90. The problem has nothing to do with the trim pot or resistors.

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PostPosted: Mon May 22, 2023 11:59 am 
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RobertJay wrote:
byoc wrote:
New production ON Semi 2N5952 don't work quite right anymore. They "work", but they just don't sound quite right. You'll either need to find NOS Fairchild 2N5952 from a trusted supplier (which is not going to be easy) or you will need to find an alternate JFET. For example, we're currently using 2SK30A in the Classic Phaser kit now, but it has a different pinout, so we had to update the PCB. The Li'l Orange Phaser is out of stock because we need to update the PCB to accept the pinout for the 2SK30A.

You could still use something like the 2SK30A in the current Li'l Orange Phaser PCB. You'd just need to twist the leads a little bit so that they go in the correct eyelets.


Someone pointed out the Lil phaser Schematic shows a 220k trimmer but the parts list calls for 100k. Did anything change? I just tested and matched transistors and it made no difference. Looking into that Trimmer, or I must have a rogue component value in there somewhere.


The trim pot value on the Phase 90 is somewhat irrelevant. It's simply a voltage divide for the bias voltage. The impedance difference between a 100k and 250k trim pot might make a difference if it weren't for the 1M/R22 resistors. A difference of impedance between the 1.125M and 1.05M series resistance is inconsequential, especially when tolerances are factored in.

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PostPosted: Tue May 23, 2023 4:42 am 
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Gotcha, I see. No worries. Between here and the emails... I don't want to overload you and be more annoying than I am already. All good. It is what it is. I tested them or so I thought. My TC-1 Tester gave me the Vgs value, I grouped those in 4's to no avail. If my testing method isn't the one to use, I'll look into that. We want the cutoff voltage, I'm going to make the Improved JFET Tester from the GEOFEX webpage . Last month it was all about germanium transistors and built the keen tester. This month is this. THANK YOU ALL!!!


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PostPosted: Fri May 26, 2023 4:20 am 
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Thanks all! I'm gonna say I have fake transistors. This batch of 5952's were the only ones bought off of ebay. I thought to match them myself and see what I can do to save a buck to no success. I only now see that the legs are NOT as they should be in the tester. The PCB calls for 5952 with a pinout for 123 as GSD. These 5952's are showing as DGS. I'm gonna match em and twist the legs and see what's up. Thanks for the help!
I also notice that N-JFETs read different legs when in the tester backwards. Bipolar ones will read them backwards, no problem. But the N-FETs do not. GDS when front facing reads as DSG when backwards. SMH. There's been confusion thrown into the mix with the PCB specifications, the new practice of matching quads, the transistors reading and acting weird in the tester and ultimately the chance that I bought bad parts. This is how we learn!!!


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