Category Archives: Electronics

Inside the 741


Ken Shirriff has written an excellent exploration of the 741 op-amp, including decapping a metal can package AD741. There’s a very cool interactive viewer so that you can click on the components in the schematic or on the picture of the die to see what each one is and does.

…The 25pF capacitor in the 741 has a very small value but takes up a large fraction of the chip’s area. You can see the capacitor in the middle of the die photo; it is the largest structure on the chip. …

Our very own XL741 is referenced in the footnotes, too.

Psychedelic Flame Soldering Kit


Last year, we released our Flickery Flame Soldering Kits with six candle-flicker LEDs in red and yellow or white and warm white, to give a fun and semi-realistic flame effect. Now we’re releasing a new Psychedelic Flame Soldering Kit with six blinky-fading-flashy RGB LEDs.

Together the auto-changing LEDs make this a bright, colorful, and kinetic light show. Perfect for holiday decorations (psychedelic Jack O’Lanterns, anyone?), luminarias, scale models, stage props, and parties.

Kit contents

These kits are fun, low-cost, self-contained, and easy soldering kits, which will be right at home both as stocking stuffers and as bite-size first projects for soldering workshops.

Clocks at Maker Faire NY

Clocks at Maker Faire

The first day of Maker Faire New York was great fun. We’ve found a several great clock projects so far, including this one, featuring image processing running on a Raspberry Pi.

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Our friends at NYC Resistor brought a wonderful papercraft seven segment display clock.

Tom, Massimo and Ahmed

At the end of the day, while talking with Tom and Massimo from Arduino, we ran into another maker with a clock project. Welcome to the maker community, Ahmed!

XL741: Principles of Operation

XL741

Our two “dis-integrated circuit” kits are the Three Fives Discrete 555 Timer, and the XL741 Discrete Op-Amp. These two kits are functional, transistor-level replicas of the original NE555 and μA741 (respectively), which are two of the most popular integrated circuits of all time.

Last year, we wrote up a detailed educational supplement for the Three Fives kit, that works through its circuit diagram and discusses its principles of operation down to the transistor level. Today, we are doing the same for the XL741 kit, and releasing an educational supplement that explains how a ‘741 op-amp IC works internally, down to its bare transistors and resistors:

XL741 Documentation (PDF)

This ability to peek inside the circuit makes the XL741 a unique educational tool. In what follows, we’ll work through the circuit diagram, discuss the theory of operation of the ‘741 op-amp, and present some opportunities for experiments and further exploration.

You can download the supplement here: XL741 Principles of Operation (1.1 MB PDF)

Additional Resources: