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I have an Confidence Boost with a JRC4558 and a 2n5088. Can these run at 18v?

I have an old Deluxe Electric Mistress that attenuates the signal when the effect is switched on. I was wanting to incorporate this internally to raise the output back to unity, but it needs to work at 18V DC.

Thanks.

This one is easy enough that I'm not going to answer it for you, but instead teach you how to answer for yourself.

Take the part name and pop it into Google or Mouser.com. In the case of the JRC4558, Mouser gives you nothing, but Google gives you a datasheet as the first link. Open it. Look for something that looks like "max supply voltage" or "Vcc". Generally, the max voltage will be the largest voltage value in the datasheet.

Do the same with the 2N5088, this time, Mouser will give you a data sheet. Look for the collector-base voltage. While you have the data sheet up, just look through it can get familiar with what sort of info it has. This way if you have a question about a part, you have one more resource to look at to help you.

Lastly, you'll also want to look at the voltage rating of any caps. I doubt you'll have any caps with a voltage rating less than 25v, but they do exist so it's worth looking at.

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-Mike

Thanks for the advice. I did as you said before I posted. My question is raised mainly due to my experience with the boost in the Overdrive 2.

JRC4558 has absolute maximum supply voltage of 18V. Overdrive 2 instructions say 18V is fine with this chip but not the mosfet op amp option. So I believe I am OK here.

2N5088 has max 35V collector to base. Sounds fine.....but BYOC OD2 instructions say 18V works with mosfet boost but not the transistor boost, even though that transistor (MPSA18) is rated at 45V collector to base. Why is it limited to only 9V???

The boost stage will distort rather badly at 18V with the MPSA18.

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“My favorite programming language is SOLDER” - Bob Pease (RIP)

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Alright then. I guess the lesser gain of the 2N5088 may allow amplification without distortion at 18V.

I'll just try it then, and if it distorts, I'll work on dropping the voltage for the booster.

I'll report results in a couple days for anyone interested in a similar application. Nice to use an old project for a working solution to a problem.

Measure the base and collector voltages for both a 2N5088 and a MPSA18 with a 9V and then an 18V supply.

Although there are a number of changes you can make to get both types of transistor functioning, I'll wait until you have posted your voltage readings.

This is incorrect, but it's not exactly something that's intuitive. The op amp's maximum voltage is +-18V, or 36V total. An op amp runs on two voltages, a high voltage (pin 8 for this chip) and a low voltage (pin 4). The audio swings between those two voltages. In most pedal circuits, the low voltage is 0V, because that's ground and it's convenient. You'll very, very often see circuits in textbooks etc. (and hence all over the internet) that run on +12V/-12v. Or +5V/-5V (which is 10V total).

I don't see any reason that the BJT circuit can't run at 18V, but there might be a bias issue that makes it not sound as good, but misbiasing is more likely to happen with the MOSFET. I've used BJT circuits lots on 18V. Maybe it's a typo or there's something I'm not seeing.

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I'm Jon. My band. Just me. Vids. PCBs: Bearhug & Cardinal: 1776 Effects. Hamlet & Blue Warbler: JMK PCBs. Flabulanche: Madbean