transistors for Univibe Clone

[EdJ]

Hi All!

Vin and i are in the stage of ordering stuff for a univibe clone from DIY Analog guitar and Bass Effects.
The unit calls for 2n5210 trannies but unfortunately we can`t find those over here.
Can anyone recommend a workable substitute for these transistors,please?

Thanks very much in advance!
Greetings,Ed

[EdJ]

To narrow it down a bit:will the unit sound different if we use 2n3904`s throughout?Btw.the site it is comming from is J C Maillet`s.
Ed

[petemoore]

Those a low gainer's .
 3904 is typically higher gain's.
 Seems like it won't hurt anything to try, so not familiar...depending on what they're used for they might work.
  Look at data sheets and see what you can find that's available inthe NPN silicon low gain category...any of these should be suitable for the category.

[EdJ]

Thanks,i`ve got the Farnell catalog in front of me so i will follow your advice.Actually i was hoping someone had tried some different ones and liked one of them best :oops:
ed

[Arno van der Heijden]

Hi Ed,

Did you read the R.G.'s neovibe pdf file on generalguitargadgets?
This is what it is says on transistors:

The transistor selections for the ‘Vibe clone are not critical. I used all 2N3904’s in my first one, and a mixture of 2N5088 and
2N5210 in my second one. The 2N5210 and 2N5088 are good all-round choices. The only transistor which really needs to be
different is the lamp driver transistor which needs to handle higher currents. The original used 2SC539 for the first transistor,
Q1, and 2SC828 for all the rest.

I think I would use 2N5088 or 2N5089 for their lower noise.

[dr]

...I used all 2N5088's in mine and it sounds great! I socketed only the bulb driver transistor,so in case it ever fries I could replace it.....

[EdJ]

thanks guys;i knew about the 5088 and i red the GEO stuff but the problem is that Farnell doesn`t have those in their catalog.
Do you think the 2n5087 will work?
The catalog says it has a minimum Hfe of250.
Thanks in advance,Ed

[Arno van der Heijden]

No!
2n5087 is PNP so it won't work.
You can order 2n5088 from Steve Daniels.

[Eb7+9]

Hi All!

Vin and i are in the stage of ordering stuff for a univibe clone from DIY Analog guitar and Bass Effects.  The unit calls for 2n5210 trannies but unfortunately we can`t find those over here ...

Ed,

I use 2n5210 as a general medium-high-gain/low-noise device for most circuits (I buy them in bulk) - they happen to work good both in clipping and linear circuits ... but any small-signal Silicon device should work fine in the Univibe Filter stages, since they're operating at unity gain (Re = Rc), and in the preamp too ... btw, I haven't figured out what's so special about the very first device in the uv-preamp ...

I think the biggest challenge in cloning a Shin-Ei, Jaxx or Univox Univibe circuit is in finding ultra wide-range cells (100ohms to 10Meg) - that's how you get a nice deep effect ... there seems to be a flood of new cells made by Silonex that might fit the bill but I haven't explored any of them yet ...

I received a schematic of the JAXX Resly-Tone from Dan Norris on Xmas eve (thx!!) after being querried by a fellow Hendrixian buddy down in the states about it, strange cosmic coincidence - some people claim that's the unit that Jimi played in '69 ... the JAXX circuit had radically different key-cap values as the later Univox circuit ... if anybody's got a Shin-Ei schematic I'd luv to see it !

... more experimentation on the way - it's a good time to be Univibin'  :wink:

hope this helps ... jc maillet

[R.G.]

btw, I haven't figured out what's so special about the very first device in the uv-preamp

It's rated for lower noise and high gain at lower currents.

ultra wide-range cells (100ohms to 10Meg) - that's how you get a nice deep effect

As important as the wide range cells is tweaking the final 100K/100K mixing resistors to get the best possible notch depth. That is one of the biggest differentiators in production univibes I've seen.

the problem is that Farnell doesn`t have those in their catalog.

Any of the BC series that is moderate to high gain (250 -700 or so) and low noise should work fine. I'm not all that familiar with the BC's but BC549 is a reasonable one... I think.

The lamp driver transistor really needs a max current rating of 100ma or so. The lamp driver transistor is what fails most often in production univibes. On my PCB layout (as available from GGG under license) there is room for a TO-220 package device to allow that to get taken care of. But many clones have been built entirely from 2N3904.

Just search through the Farnell catalog for NPN's with BVceo>30V, hfe/current gain of 250 or more, and low noise. Get a 100ma rated device for the lamp driver.

[EdJ]

Thank you all very much!I will go through the catalog again and order the ones like you said.Will let you know tomorrow.
As for the cells:one measures them with an Ohmmeter in completely dark and with a lightbulb on it and those are the values right?
Greetings,Ed

[EdJ]

Hi again!
I chose the BC337-40 transistor.It meets the values mentioned beatifully.
Hope it will does the trick!
greetings,Ed

[Craig V]

tweaking the final 100K/100K mixing resistors to get the best possible notch depth. That is one of the biggest differentiators in production univibes I've seen.

I was wondering, would I replace both of these resistors with a single pot or a double pot?  If it's a single pot, would the middle pin be the "output" and I would just connect pins 1 and 3 to before where the 100ks used to be?

Thanks.

[petemoore]

How often is resistance Across a pot [lugs 1&3] critical?
 I know this is an extremely general question...
 It seems that a 200k pot would divide and make it easy to adjust the fractions, in place of a 100k's divider.

[R.G.]

I was wondering, would I replace both of these resistors with a single pot or a double pot? If it's a single pot, would the middle pin be the "output" and I would just connect pins 1 and 3 to before where the 100ks used to be?

You could do either, but the premium way to do it is to lower the resistors to, say, 75K or 82K each, then use a 50K pot with the outside lugs attached to the two resistors, then take the output off the wiper. This connection lets you trim for the best sound by ear.

What's going on is that the depth of a phaser depends on getting a good cancellation in the notches. The imperfect phasing stages in a univibe have some signal loss in each stage, so the cancellation isn't always perfect. The trimmer lets you adjust out not only the +/- 5% variation on the resistor value but also the change in gain over the phase chain.

You can also set it by ear to best cancellation with a single fixed 100K against a 150K or 250K pot wired as a series variable resistor for the other "100K" resistor, then measure the pot setting resistance when it sounds best and stick in a fixed resistor when you get to the "best" value by ear.

I chose the BC337-40 transistor.It meets the values mentioned beatifully.

The BC337-40 datasheet specs look great for this. Be **certain** you watch the pinouts on these when you put them and you'll be fine, I think. I don't notice any noise specs on it, but you'll probably be fine.

[Gearbuilder]

Hi
Craig you should connect 1 aand 2 at the place of the 100k ,in this manner you could tweak it  to optain  the best phase cancelation( when the resitors are same)
Bruno