#1
Hey guys I'm building a fairly simple compressor pedal and in the schematic it lists an IC1-4558 but the site I'm ordering my components from doesnt seem to sell this IC. Is there an IC i can use to replace it?

http://www.tonepad.com/project.asp?id=5

Theres a layout of it on that page. (I'm using the second layout).

Heres the list of IC's that BYOC offers.

http://www.buildyourownclone.com/storeics.html


Any help / tips would be appreciated. I've built 1 boost pedal before but never anything with an IC so my knowledge is beginner at best.
My Gear:
Schecter Hellraiser FR Special.
EpiG400 lefty w/Dimarzio X2N/ Irongear Hot Slag
Peavey 6505+112 (head)
2x12 Cab w/ WGS v30 / gt65
GFS Tuner
TS-9 (Keeley ish mod)
Dunlop GCB-95 Wah truebypass
ICP Gstring Decimator
#2
4558's are common as flies. almost any dual op-amp (operational amplifier) can replace it (most if not all duals have the same pinout [pin assignment]). you should be able to get all the parts from smallbearelec.com. the link you posted has it. it's the JRC4558, third from the top.

protip: letters before the part number usually are just brand-specific. so a LM4558, JRC4558, etc are all the same chip, just made by different people. when serching for parts, you can almost always omit those letters at the beginning.

any letters following the part number (like 4558D) are just a revision. so like a 4558D is a revision (improved version) of the 4558C.

Extra fun: the beginning letters just tell you who made it. LM is from National Semiconductor and JRC [also called NJM] is from Japan Radio Corporation, and TL is from Texas Instruments.
Last edited by Invader Jim at Jun 30, 2011,
#3
Okay cool thanks a lot jim.

Also a couple more questions on this build. How would I add a DC power jack to the schematic? Would it just replace the 9V battery in?

And also I want to add an LED to show that its on/off. Is this difficult in any way? How would I go about it.?

Thanks guys.

EDIT* Almost forgot. On smallbear I can't seem to find 4.7M resistors anywhere? It seems odd they don't have them. And what trim pots do you guys prefer for pedals? (what type I mean)
My Gear:
Schecter Hellraiser FR Special.
EpiG400 lefty w/Dimarzio X2N/ Irongear Hot Slag
Peavey 6505+112 (head)
2x12 Cab w/ WGS v30 / gt65
GFS Tuner
TS-9 (Keeley ish mod)
Dunlop GCB-95 Wah truebypass
ICP Gstring Decimator
Last edited by bj_squeelie at Jun 30, 2011,
#4
If you look on SmallBearElec.com and go to their jacks section, they have a switching DC jack so that you can have both a battery and an optional DC supply.

It is very simple. http://www.geofex.com/article_folders/bypass/bypass.htm


Http://www.smallbearelec.com/Detail.bok?no=271
#5
Hey guys I got all my parts ordered they should be here this week sometime. I got a couple more questions before I start it.

1. Will IC sockets fit any ic? I saw them on a site and they seem terrific for like 30 cents.

2. I plan on making it true bypass. Does anyone have an easy schematic for offboard wiring for true bypass? The offboard wiring is really my biggest worry at this point.

3. GROUNDING. I understand grounding in general, but when stuff says "all points soldered to ground" I get confused as to what I'm actually soldering to what, and what all needs to be grounded.

4. I'm going to put in a dc jack to run with my one spot and just solder a batter snap to it (with opposite poles so the snaps will fit) and snap that to the battery connector in the circuit for power, that way if I ever would want to use a battery I just unsnap it and attach a battery, taking the dc jack completely out of the circuit. Anyone see any flaw in my plan?

Thanks guys. =)
My Gear:
Schecter Hellraiser FR Special.
EpiG400 lefty w/Dimarzio X2N/ Irongear Hot Slag
Peavey 6505+112 (head)
2x12 Cab w/ WGS v30 / gt65
GFS Tuner
TS-9 (Keeley ish mod)
Dunlop GCB-95 Wah truebypass
ICP Gstring Decimator
#6
Yes, and no.. IC sockets can fit different types of IC packages, you want DIP sockets, and if you bought from Smallbear, you'll be set.

First google search of "True Bypass"

Ground is merely a reference voltage, it is the 0 volt reference for the circuit. Typically we (pedal builders) use the negative terminal of the battery. All grounds are connected, this just means that everything that is to be grounded is connected to that negative terminal some way, be it a component leg soldered to it, a PCB trace, or a wire.

Can you rephrase 4? If you use the switching DC jack from Smallbear, you can solder the battery snap to it, and it only uses power from the battery when nothing is plugged into the DC jack.
#7
Okay thanks a lott. I'm not sure which dc jack I purchased but the idea was to solder a battery snap to the jack with the poles backwards and snap that to another battery snap that is connected to the circuit. I really don't even want to put a battery in there, but I want the option to use one to still be available after I'm finished. So, in theory, if i pull the snaps apart and connect a battery to the 2nd battery snap mentioned it will then power the circuit instead of the dc jack. I'm fairly sure this is a valid way of doing it but if nothing else I will just find one of the switching jacks and call it good.
My Gear:
Schecter Hellraiser FR Special.
EpiG400 lefty w/Dimarzio X2N/ Irongear Hot Slag
Peavey 6505+112 (head)
2x12 Cab w/ WGS v30 / gt65
GFS Tuner
TS-9 (Keeley ish mod)
Dunlop GCB-95 Wah truebypass
ICP Gstring Decimator
#8
Hey guys I'm pretty much done with my compressor but I'm wondering. Is the LED in this true bypass wiring required for the pedal to work? I don't have the LED wired yet becuz i need to pick up a resistor for it but I plugged it in and it didnt sound too pleasant as is. It reduced the volume of my amp to barely audible no matter which way i turned bias knob or level knob but it seems to bypass perfectly fine.

Is it just because the LED isnt wired in? or any idea what is wrong with it?

Here's my true bypass diagram thingy.
http://www.beavisaudio.com/techpages/PedalHacker/LooperWithLED.gif

thanks for any help.
My Gear:
Schecter Hellraiser FR Special.
EpiG400 lefty w/Dimarzio X2N/ Irongear Hot Slag
Peavey 6505+112 (head)
2x12 Cab w/ WGS v30 / gt65
GFS Tuner
TS-9 (Keeley ish mod)
Dunlop GCB-95 Wah truebypass
ICP Gstring Decimator
#9
shouldn't be necessary no.. just connect things without it
Epiphone Les Paul Plus Top
Jet City JCA5212RC (SLO Modded)
Ibanez WD7 Wah
Mad Professor Sweet Honey Overdrive
TC Electronic Flashback Triple Delay
TC Electronic Trinity Reverb
#10
leds just tell you when the thing isn't bypassed. they are not necessary for the functionality of the circuit.

since it works fine in bypass mode (as it should) then the problem is in the circuit itself, and probably not the switch wiring (check to see if the jacks are properly connected to the "un-bypassed" side). not much to say except check the cables and batteries/power supply, check every connection against the schematic, looke for shorts and opens, be sure you didn't overheat a semiconductor component (like a diode or IC, and to some extent a resistor)... really just go through all the basic troubleshooting checklist.

not much any of us can do from here...
Last edited by Invader Jim at Jul 19, 2011,
#11
Hook up the input and the output of the circuit directly to the input and output jack tips. For now don't use the switch. This will eliminate any switch wiring issues and verify that the problem is the circuit.
#12
Hey guys I got it to work a little better by replacing 2 capacitors, but its still lowering the volume of my amp significantly. I've checked the IC pins for continuity but will that tell me if I fried the IC? Could it be a transistor also? I'm not using the diode recommended in the schematic, Idk if that matters?
My Gear:
Schecter Hellraiser FR Special.
EpiG400 lefty w/Dimarzio X2N/ Irongear Hot Slag
Peavey 6505+112 (head)
2x12 Cab w/ WGS v30 / gt65
GFS Tuner
TS-9 (Keeley ish mod)
Dunlop GCB-95 Wah truebypass
ICP Gstring Decimator
#13
check the pinout of the IC. if it is correct, try replacing it with a new one. same with the FETs. the diode type shouldn't matter as long as it is Germanium. idk what a Silicon diode will do in this circuit, probably not much difference (though I could be wrong). the only difference between Si and Ge is that Ge has about half the forward voltage drop.
Last edited by Invader Jim at Aug 23, 2011,