Maestro FZ-1 Beginners Build

[PJ03029174]

Hi

I'm really excited to be learning electronics and am putting together a shopping list for an Maestro FZ-1 i would like to build by Xmas.
I'm struggling to find the 20uf / 12v Sprague Electrolyic caps. I'm trying to get as close to the original as possible and have 3 2N270's and ordered some Carbon Comp resistors. I'm just struggling with the Caps. Could anyone point me in the right direction? the closest i've found so far is ( Sprague Capacitor 20 UF MFD 16 VDC TE 1157 30D NOS )
Not sure what half the acronyms are but im guessing its a 20uf 16v? Is that the closest im going to get? and is the higher rating a problem?
I'd really appreciate the help
Pete

[vigilante397]

Hi

I'm really excited to be learning electronics and am putting together a shopping list for an Maestro FZ-1 i would like to build by Xmas.
I'm struggling to find the 20uf / 12v Sprague Electrolyic caps. I'm trying to get as close to the original as possible and have 3 2N270's and ordered some Carbon Comp resistors. I'm just struggling with the Caps. Could anyone point me in the right direction? the closest i've found so far is ( Sprague Capacitor 20 UF MFD 16 VDC TE 1157 30D NOS )
Not sure what half the acronyms are but im guessing its a 20uf 16v? Is that the closest im going to get? and is the higher rating a problem?
I'd really appreciate the help
Pete

Absolutely not a problem at all. The higher rating just means it can handle more voltage before it explodes. So if you're running you're pedal at 9V, it doesn't matter if your caps are rated at 12V, 16V, or 500V as long as they fit on the board. Generally the rating listed on a bill of materials for a build will be a lowest suggested rating, meaning anything above that is fine and there are no negative effects to having higher rated capacitors.

[PJ03029174]

Absolutely not a problem at all. The higher rating just means it can handle more voltage before it explodes. So if you're running you're pedal at 9V, it doesn't matter if your caps are rated at 12V, 16V, or 500V as long as they fit on the board. Generally the rating listed on a bill of materials for a build will be a lowest suggested rating, meaning anything above that is fine and there are no negative effects to having higher rated capacitors.

Thanks vigilante397 was hoping that was the case!

[PJ03029174]

Got another quick question, i've got hold of 3 x RCA 2N270's for the project and borrowed a DCA55 to measure them, the results are

Conditions = Test Current=2.5ma,Base Emitter =0.29V, Test Current=5.16mA

2N270 (#1) 177hfe, 0.21mA
2N270 (#2) 155hfe, 0.23mA
2N270 (#3) 192hfe, 0.27mA

Everyone says to put the leakiest 2N270 in the Q2 position, is 0.27mA a good leaky value for a FZ-1 replica?
I've managed to pick up another stray 2N270 on the cheap which should arrive in a few days and am looking forward to testing it

[smallbearelec]

With much respect and love, the FZ-1/1A is a poor choice for a beginner build...too many parts, too many stages, too finicky to line up. But you have already put some money into buying parts (on e-Bay?) so I'll offer a few suggestions that I hope will give you good direction. I have cloned the FZ-1/1A, and this article

https://www.smallbearelec.com/Projects/FuzzE-One/FuzzE-One.htm

explains what I did and why.

IME, the 2N270 that you describe are a little too "good", especially for Q3. This is actually a "high-quality" sort of problem; I would tell you to reserve the 2N270s for builds that want relatively low leakage parts and find pieces that would normally be trashed to use in this build. This is only difficult if you insist on "authenticity", meaning finding either 2N270 as in the FZ-1 or 2N2613/2614 as in the FZ-1A. If you care more about the tone, it's the gain and leakage that matter, not the part numbers. I have lots of suitable devices, or some of the residents here may have remainders that they would sell you inexpensively.

Breadboard It First!! If you expect it to sound "right", you have to expect to tweak the bias to match the devices you wind up with. Also, again if you don't insist on complete "authenticity", you'll get a far more usable pedal if you build NPN rather than PNP and include a simple voltage regulator to drop 9 Volts to 1.5. Building NPN was not practical back then, because NPN germanium was too expensive. Today, leaky NPN germanium is easy to find, and, for the moment, not expensive.

Happy Construction, and let us know how it goes.

Regards
SD

[LucifersTrip]

a couple notes...

smallbear, I believe the OP is building an FZ-1 (3V supply, thus the 2N270's), so don't know how helpful the E-One guide will be.
I don't think you can just double the voltages you've set as "goals", though it is very difficult to find voltages listed from an original FZ-1 (at least I couldn't when I built one a few years back).

I do have numerous vintage 60's knockoffs of the FZ-1A (1.5V supply) and none have Q3C voltage as low as .6-.8 as in your E-One guide. Most are in the 1 - 1.2V range.  When the voltage starts to drop to the .6-.8 range, it usually gets noisier.

op, I think the hfe's of your 2N270 are pretty high. It can easily work with those gains as long as the leakages are what you need, but it may not be as easy to keep the circuit as quiet and you'll most likely have more leakage fluctuation with temperature. The 2N270's I've had have always been under 100 hfe and a quick check on one datasheet shows 70 hfe as typical, which would be very reasonable for that circuit.
http://transistor-spravochnik.ru/description/2n270/2351

anyway...good luck. As SB noted, it's not the best choice as an or early build, but go for it!

[smallbearelec]

smallbear, I believe the OP is building an FZ-1 (3V supply, thus the 2N270's)

True.

so don't know how helpful the E-One guide will be.

I agree that the voltage readings will differ. However, I hope that my description of lining up a set will be helpful if the op goes forward. The regulator idea can easily be tweaked to provide 3 Volts just by removing a couple of diodes.

op, I think the hfe's of your 2N270 are pretty high. It can easily work with those gains as long as the leakages are what you need,...The 2N270's I've had have always been under 100 hfe and a quick check on one datasheet shows 70 hfe as typical, which would be very reasonable for that circuit.

I agree...when we line up sets for this build, we look for parts that are relatively low in gain, but with fairly high leakage, like in the 500 microamp range. This is especially important for Q3, because it needs to leak enough to forward-bias the Base and so turn the device On.

[PJ03029174]

Thanks so much for the responses smallbearelec & LucifersTrip.
I was/am in the process of buying parts for a Dan Armstrong Orange Squeezer clone for myself but have started on the FZ-1 as a present for my Dad for Xmas. The 2N270's i bought were off an Aersospace Supplies website and i thought they were pretty high gain when i tested them. I'm not sure how acurate the Leak DCA55 is with the HFE values. I know there is a circuit you can make to test Geranium Transistors for HFE and Leakage so i could make myself one of those.

Thanks for the tip about breadboarding smallbearelec. Bought one last week
I'm trying to keep all the parts original because its a gift and i know he'll apreciate the attention to detail.
The 2N270's wern't too badly priced, about half of the ebay price but they came without measurements. I've got some time so am happy to keep my eye out for 2N270's with lower gain and higher leakage values.

I managed to find some NOS 20uf / 12v Sprague Electrolyic caps. I think they are from the 70's. I know that the caps only last about 10 years, it that with alot of use? or would NOS ones have deteriorated just as bad?

Thanks again

[smallbearelec]

I managed to find some NOS 20uf / 12v Sprague Electrolyic caps. I think they are from the 70's.

They are likely still good. Sprague TE series were the "high-priced spread" when I was a kid. I just found a bunch of 5 mf. in that series and tested them with the cap scale of my multimeter. Values were all within tolerance.

[PJ03029174]

My ebay lucky dip single 2N270 has just arrived ... an ETCO 2N270. I've never seen this make before, has anyone used them? I'll test it tonight and report back

[PJ03029174]

Just got home and tested the ETCO

PNP Geranium Transistor
HFE = 57
Test Current = 2.5mA
Base Emitter = 0.31V
Test Current = 5.13mA
Leakage = 0.00mA?

Does this look right?

[LucifersTrip]

Just got home and tested the ETCO

PNP Geranium Transistor
HFE = 57
Test Current = 2.5mA
Base Emitter = 0.31V
Test Current = 5.13mA
Leakage = 0.00mA?

Does this look right?

yes, the Peak shows 0 leakage when it's very small (maybe under 50 uA).

I've got some time so am happy to keep my eye out for 2N270's with lower gain and higher leakage values.

there's no harm in breadboarding the various combos you have already

[smallbearelec]

ETCO 2N270. I've never seen this make before, has anyone used them?

Electronic Transistors Corp. was a small maker that had a fab on Northern Boulevard in Queens, not far from where I was raised. Their parts were pretty good, and they still turn up as surplus.

Based on the measurements you have, this one would make a good Q1; low leakage is actually good in that stage.