BA482 diode equivalent for Bootleg?
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BurntFingers
Well-known member
Anything with a forward voltage of 1.2v should be the equivalent. Whether that's a single unit or some others in series.
Nostradoomus
Well-known member
1.2v is the max Vf for that diode, but anything from .6 to 1.2vf should work. Many small signal diodes drop around .6-7 so just socket it and play around, there’s no magic sauce in diodes.
Thanks for the reassurance, I figured/hoped as much but wasn’t sure if there was anything special about using “band switching diodes” for clippers
Nostradoomus
Well-known member
If they weren’t being applied as clippers in this circuit you might have an issue, but you can sub them out here for your usual 1n4148.
Lord knows I’ve got plenty of those!
The circuit also has a 1N4002 instead of a 1N4001 for clipping for seemingly no reason; I’m starting to think that mayhaps this JHS design is full of arbitrary component decisions...
Nostradoomus
Well-known member
Probably just what they could get cheapest in bulk as far as the 1n4001/2 goes. The BA482, who knows...just to confuse and intrigue us nerds haha
K Pedals
Well-known member
I think these are pretty much the same thing
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Chuck D. Bones
Circuit Wizard
Vf depends on diode current (Id). Usually, Vf is given in the data sheets at max rated current or 100mA. Pedals run clipping diodes at no more than a few mA. This pedal can drive them up to about 7mA. My point is that the only way to really know Vf is for the datasheet to contain a graph of Id vs Vf (or for some nice person to post a plot of Id vs Vf ? ) and you know Id for the pedal in question. Otherwise it's a WAG.
I'm with Nostradoomus, put in sockets and try different diodes. Try Schottkys or germanium even. How it sounds is all that matters.
I'm with Nostradoomus, put in sockets and try different diodes. Try Schottkys or germanium even. How it sounds is all that matters.
Here's those plots. Unfortunately, the BA482's datasheet uses a linear scale for the forward current vs voltage. I *think the curve for the BA482 looks exponential-ish which would look linear in a semilog plot, but who knows what the slope would be...
I tend to agree that the 1N4148 would be an ok replacement in this case. The Vf is close enough, which, as others pointed out, is probably what really matters in the circuit.
I'm wondering if the capacitance of the part has anything do do with the choice? BA482s have very low (0.8pF) capacitance compared to the 4148s (4pF) and the 400xs (15pF). With the 51pF in parallel to the diodes, that might impact some of the behavior. The 4148 is at least the same magnitude, so I'd pick that over the 400x.
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Chuck D. Bones
Circuit Wizard
The plot on the left is basically useless for pedal circuits since the diode currents rarely exceed 5mA and in most cases are below 1mA. Diode capacitance for any of those devices is negligible at audio frequencies. The three diode characteristics we care about in pedals are leakage current (Ilkg), forward voltage (Vf) and series resistance (Rs). Most of the time, it's only Vf we care about. Notice how the curves on the right bend over at high current? That's the effect of Rs.
BTW, all semiconductor diode curves are exponential at low foward current and become a straight line (plotted on a linear scale) at high forward current where Rs dominates and at negative voltage where Ilkg dominates.
BTW, all semiconductor diode curves are exponential at low foward current and become a straight line (plotted on a linear scale) at high forward current where Rs dominates and at negative voltage where Ilkg dominates.
FWIW I did get some BA482s from overseas via eBay. Sounded pretty identical to 1N4148s (or, rather, as different from one pair of 1N4148s as any pair of 1N4148s sound from any other pair of 1N4148s), may have had a bit more clipping headroom but nothing terribly obvious (and I wasn't doing a blind comparison, so I may have been expecting it and have some confirmation bias).
LEDs were noticeably brighter and had higher headroom, as expected.
So yeah, BA482s are closer to 1N4148s than LEDs, which makes sense.
LEDs were noticeably brighter and had higher headroom, as expected.
So yeah, BA482s are closer to 1N4148s than LEDs, which makes sense.
Chuck D. Bones
Circuit Wizard
Dan0h
Well-known member
I found this old thread helpful for the Mojito build. The bootleg which is the moonshine Calls for Ba482 but the effectslayouts version of the moonshine subs 1n4148s. And to second that @wintercept suggested 1n4148s are a worthy sub as well. Sounds like a winner. I’ll do a build report when it’s done.
Old threads rule.
Old threads rule.
Chuck D. Bones
Circuit Wizard
The Mojito is much more sensitive to Vf on the hard clippers than the Bootleg. I can hook you up with some BA482s or you can use JFETs (wire D & S together for the cathode, G is the anode). Bjorn Juhl uses JFET clippers in some of the circuits that the Mojito is based on.
BTW, I personally do not consider Effectslayouts to be a reliable source. I've seen to many uncorrected errors there.
BTW, I personally do not consider Effectslayouts to be a reliable source. I've seen to many uncorrected errors there.
Dan0h
Well-known member
I would happily PayPal or Venmo you to cover them and shipping if you have extras to spare.
Dan0h
Well-known member
Or jfets are fine I have a pile of those is one type better? Jfet wise.I would happily PayPal or Venmo you to cover them and shipping if you have extras to spare.
Chuck D. Bones
Circuit Wizard
I think any JFET will work. The BJFe Model G used 2N5457. The Model H used 2N5952.
I just checked my diode V-I data. The V-I curves for BA482 and 2N2952 are nearly identical. Other JFETs should be similar, but I don't have data at the moment.
I just checked my diode V-I data. The V-I curves for BA482 and 2N2952 are nearly identical. Other JFETs should be similar, but I don't have data at the moment.
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