Emerson Em-Drive

[inefficiency]

Hey guys, I just threw one of these together 10 minutes ago because I figured it's the simplest layout I've seen on here and is one of the few builds on here I know I'll have what I need to build it 100% of the time.

Now, the layout says that it requires a 2n5088 or similar. How similar does it need to be? I figured I could probably throw any NPN transistor I have in there. What do you guys think?

Guys are saying this pedal is awesome as a boost, so I thought a JFET or something might be involved, but I guess not.

[Silver Blues]

I think the original was an MPSA18.

[IvIark]

I'd socket and try a few.  Different people post different recommended transistors for these things but unless you're using the same gear as them you just aren't going to know what will work best with your guitar, effect chain, amp.  Whenever I'm not sure I'll just socket and try everything I've got until I like something.  But if you have used an original and like it, then the 2N5088 would be a good choice as it was used in the original I think.

[rocket88]

i have to check mine, but i think i used an MPSA18 in the end. if you read the comments on it i remember someone posted about the differences in tone they got with different transistors, like one was a tad more bassy, one had better breakup, etc. i was thinking what about putting in a NPN Ge transistor and seeing what happens, but i boxed mine in a 1590A box, so no room to do so.

btw, in mine i changed the input and output cap so i could use it for bass too, and kinda like it. it adds a little to the tone, sorta warmth or roundness to my tone. it's hard for me to find the words i'm looking for to describe, i might have to make a clip of it.

[inefficiency]

Yeah, I have some MP38s that I could have tried, but I'm doing it in a 1590A as well.

I'll need to grab some MPSA18s because they seem to be a pretty popular choice for a lot of pedals.

I think Mark is right about it just being a personal thing dependent on what you want and what your gear is. I guess when there's this few components, whatever components you change will make a pretty big difference.

[rocket88]

correction, i just opened mine up and i used a 2n5089, might go back and play with the transistor again and see how the tone changes. in mine i used the layout johnk posted, which was the same as marks, just with a trimmer for the bias adjustment, so i could put in whatever i want and be able to set it just right. also, i just got some more mpsa18's as well as a few others because over here i noticed people starting to ask stupid prices for low numbers, so i got 200 of them, plus 200 of a few other commonly used transistors to make sure i don't run out anytime soon, but i'm sure i don't have nearly the stock mark has .

[inefficiency]

The trimmer is a good idea. I didn't bother with this one because I don't have any and I just wanted to knock it together in 10 minutes.

I really like the idea of mega simple circuits because the purist in me likes that it isn't doing a ludicrous amount of messing with the tone and it lets all the subtleties through. You can hear more of what kind of pickups you have, what woods the guitar is made from, what amp you're using etc...

On the other hand, I love the MXR blue box and stuff like that which completely removes any semblance of what your original tone might have been .

Where did you pick up the MPSA18s? They have them on RS for £2.75 for 50. Anyone got any suggestions for what else might be worth getting?

[rocket88]

I got them on eBay from dpi4parts on eBay I think it ran me like $12 or so. I order a ton from him. Remember I can get stuff and send it if it's cheaper.

[inefficiency]

Cool, thanks a lot! I will check them out and let you know if I need any shipping assistance!