Bill of Materials - Digi-Key Order Form

MegaSquirt Hardware Version 2.2

This is the MegaSquirt V2.2 ordering form for Digi-Key. It is based on the official MegaSquirt BOM, and will allow you to assemble the MegaSquirt® with 'partial kit' (from the the Bowling and Grippo website) and case. Thanks to Eric Fahlgren and Perry Harrington for the Javascript and other great ideas; and to Scott Campbell, Dan Houlster, Perry, Dirk, and Sten Thornburg for comments and suggestions on components. Note that some additional parts will be required, as noted near the bottom of the form. (There is also a UK Digi-Key BOM for MegaSquirt® created by Tim Bennett at:

If the default quantities are used, the price for Digi-Key parts for a 'partial kit' should be $50.21 per set, as of July 2005.

Quantities are as required for MegaSquirt, except where minimum quantities are required.(Note: the calculated total on this form may be higher than Digi-Key indicates because you may get some quantity discounts depending on your order size).

Click the clear button below if you need to clear any open orders with Digi-Key. Then press the 'back' icon to return to this site and start your order.

With this form, you can purchasing components for 'partial kits' from the Bowling and Grippo site, which include the PCB, pre-programmed U1, U3, and U7. Components for the Bowling and Grippo MegaSquirt® partial kit(s) are $50.21 each as of July 2005. To order complete the following four steps:

  1. Choose the number of kits you want parts for:

    I want parts for MegaSquirt kit(s).

    Verify that you have the quantities you want for each item below. You can change them to the numbers you want.

  2. Then send your order to Digi-Key:

    Note: If you get an error for the first item, simply click on the 'Add List to Order' button on the Digi-Key site, and the 'erroneous' item(s) will be added.

  3. You will be redirected to Digi-Key to verify your order, payment method, and shipping details.
    • If you are purchasing parts for MegaStim and/or the relay board, do not finalize your order. Return to the ordering page and complete steps 3 and 4 there.
    • If you are NOT purchasing parts for MegaStim or the relay board, check the quantities on the Digi-Key site, and proceed to the next step on this page.

  4. Click the 'finish order' button at the bottom of the Digi-Key page, and follow the instructions there. The order will not be complete until you have finished this step. You can re-do your order by returning to this page at any time before finalizing your details with Digi-Key.

Here are the other parts you'll need to build your MegaSquirt: Some MegaSquirt® Related Links: Wiring Harness - RS Autosport offers wiring harness kits for MegaSquirt® EFI Controller, with properly labelled and colored wires in appropriate sizes. You can find out more at their website.

LMB EAS-300 case - you can purchase the case from HdB Electronics (650-368-1388) in single unit quantities. Your choice of natural aluminum or black anodized. This is where the Group Buy orders for the case were placed.
Or you can get the EAS-300 Enclosure [style 4006 - 4.124" x 1.582" x 6" w/ heavy radiused (H) ends] at:
You might also try Fry's, they have one that measured 6 x 4.17 x 1.56. It costs $15.95.

Nylon Screws - 4/40 - Digi-Key P/N H550-ND - 0.0926ea. & Nylon Nuts - 4/40 - P/N H616-ND - 0.105ea. You need 6 of each, but there is a 100 minimum quantity for each from Digi-Key. You can try locally, look for them in hobby shops that sell radio control hardware. You CAN substitute steel screw hardware. Just be careful with the plastic FETs, make sure the metal screws do not cut the plastic and short things out. For the flyback transistor and the voltage regulator there is no worries - the only thing you may want to do afterwards is put a dab of fingernail polish or similar on the screw/nut interface to help prevent them backing off due to vibration.

Cable - You will also need a 'straight-through' DB-9 cable to connect MegaSquirt® to your computer for set-up and tuning. Digi-Key sells suitable cables:

Either will work, or you can pick one up locally. Look for a VGA computer monitor cable.

Sockets - If you are new to electronics assembly, you may want to solder in sockets for all the chips. The kit includes a socket for the 40-pin CPU. To socket the others you will need:

The sockets allow you to correct your mistake if you install an IC backwards, and also prevent too much heating of the IC while soldering.

Boot Jumper - If you want a 'proper' boot jumper (instead of using a bit of snipped off lead or jumper wire), the header is 103321-2-ND (32ยข) and the jumper itself is S9002-ND (10 for $1.31). You can also use a micro-switch mounted to the case for this purpose.

Don't forget that you will need a Willette Programmer to program your blank processor if you haven't purchased a partial kit from Bowling and Grippo.

MegaSquirt Site

MegaSquirt Forums

MegaSquirt FAQ


* D1, D2, D3, D4, D8 - The 5.1v Zener diodes are optional since the Motorola processor has overvoltage protection on the analog inputs. Diodes D1 to D4 are NOT installed or included with this BOM - do not place jumpers in their place, just leave these locations open. The processor provides sufficient input protection, these diode are not needed. Once again, do not jumper these locations, just leave them alone - put nothing there. For most installations, diode D8 is not needed either. The diode is needed if the ignition system has a large offset bias - most systems do not have such a bias. So, to start, you can either solder in a jumper wire in this location, or, you can install the diode D8, and then install a jumper around the two leads of the diode - in effect shorting it out. The latter will allow you to snip the jumper later on if needed, putting the diode back in circuit. Note that the MegaSquirt® will not work on the stimulator if the D8 diode is installed but not jumpered.

** Q3, Q5, Q9, Q10, Q11 - The ZTX450 will work as a drop-in replacement for the 2N2222A. The package is different (TO-92) such that the leads are in-lined, but it is in the "E-B-C" order just like the 2N2222A. For the metal-can 2N2222A, if you hold the device, looking from the top, with the tab pointing towards the 2:00 position on the clock, the emitter is at 12:00, the base is at 9:00, and the collector is at 6:00. For the ZTX450, if you hold the flat side facing left (or 9:00 on the clock), looking from the top again, the emitter is on the top or 12:00 position, the base is in the center, and the collector is down at 6:00. Simply bend out the center lead towards the flat side (towards the 9:00 position) and the part will drop right in the hole.

*** Q1 - TIP42C is an approved substitute for TIP32 that has also been specified in older versions of this BOM.

**** U7 - IXDI404PI-ND is a replacement for MC33151P FET driver - 8 Pin DIP. If you prefer the MC33151, you can order samples at:,4317,MC33151,00.html

Click here to go back to the MegaSquirt® FAQ

MegaSquirt® and MicroSquirt® controllers are experimental devices intended for educational purposes.
MegaSquirt® and MicroSquirt® controllers are not for sale or use on pollution controlled vehicles. Check the laws that apply in your locality to determine if using a MegaSquirt® or MicroSquirt® controller is legal for your application.
©2004, 2005 Bruce Bowling and Al Grippo. All rights reserved. MegaSquirt® and MicroSquirt® are registered trademarks. This document is solely for the support of MegaSquirt® boards from Bowling and Grippo.