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:

 

 

 

Another take on Twisted Wire Bundles

Steve W. wrote in to share his improvement on the method for making wire bundles we wrote about:

 I’ve used the bend-it-over-and-stuff-it-in-the-chuck approach, but was not fully happy with it.

Binder clip on wood piece for drilling

So I drilled a 1/8″ hole in the back of a binder clip.  The drilling is easy if you clip a ~3/8 scrap of wood.

Wire twisting jig in drill chuck.

A 4-40 SHCS screw long enough to allow me to actuate the clip was not threaded all the way to the head, so I used a 1/4″ spacer between the binder clip and the 4-40 nut.  (Pan head screws are usually 100% threaded, but I would have had to look in the dreaded ‘other’ box to find one of those). Having the nut up against the chuck acted as a lock-nut.  I had been surprised when I first tried this that I did not have to work harder to keep it from loosening.  I had expected I might need a lock washer, and/or a second nut to lock the first.

Just grabbing the wires with the binder clip (my original plan) was not secure.  So I wrap the wires 180 degrees around a screwdriver bit and put that in the clip.

Works great, and it is quick to pop in and out when twisting many groups of wires.

Thanks for sharing your hack and sending the photos!

Hackaday Prize Deadline

The deadline for the Hackaday Prize is just a month away now!
BUILD SOMETHING THAT MATTERS
The creative energy and years of experience found in our huge community of Hackers, Designers, and Engineers is waiting to be unleashed. Let’s use that potential and move humanity forward.
We’re helping to judge the Best Product category, which has fewer than 50 entrants so far. The prize for Best Product is $100k and 6 months free rent in the Hackaday Design Lab with mentoring.
One example project is Eye of Horus, Open Source Eye Tracking Assistance, to increase accessibility for people who are disabled or physically separated from a work area.
Another entrant is DIPSY, an FPGA module in a DIP-8 package, shown here with an LED daughterboard in 6-pin DIL format.
Submissions are due August 17, so get your entries in right away! If you have questions or want feedback on your project, there’s a meetup on the hackaday prize channel on July 21 at 6 pm PDT.
We’re looking forward to seeing your entries!

Intel Open Source Hardware Advisory Panel

I’ve been participating in the Intel Open Source Hardware Advisory Panel this year.

… Intel hosted a series of conversations with the company’s Open Source Hardware Advisory Panel – a group of key enablers in the global open source hardware ecosystem – about licensing, best practices, sustaining development communities, business models, path to product, Shenzhen, and the evolving relationship between the global maker movement and chip manufacturers.

We’ve had some interesting conversations and Intel has been publishing video from our meetings. At the session titled Open Source Hardware Communities, Case Studies, and Guidelines, I talked about the EggBot and its communities of users; Adrian Bowyer talked about the RepRap community; André Knoerig about Fritzing; and David Scheltema about Make and Maker Faire. I enjoy seeing these issues being grappled with, and hope that our conversations will help others as they think about these topics. Videos from the sessions can be found on the panel page at Intel.

STEAM Fest 2015

I took a heap of pictures at the 2nd annual Silicon Valley STEAM Festival at the Reid Hillview Airport in San Jose today. This event brings out an eclectic mix of hobbyists, scientists, and enthusiasts showing off what they do. Below are a few of my favorite moments.

RC planes

The local RC aircraft enthusiasts not only displayed their aircraft, but also put on an airshow. They also fly at Baylands Park, and encouraged coming to see them on Sundays.

Huey

Vintage aircraft flew in to be displayed.

Leopard shark

Local science institutions brought their mobile displays, including leopard sharks from the Marine Science Institute.

Firebots outreach

Robotics teams, (including our very own Firebots) were demonstrating their robots in the midst of cars on display. You can find more robots, aircraft, automobiles and sharks in my album here.

GeekMom reviews Build-It-Yourself Science Laboratory

Sam over at GeekMom just posted a thoughtful and kind review, Bringing Science Home Again: ‘The Annotated Build-It-Yourself Science Laboratory’.

This is exactly what was needed. So much of home-based experimentation right now is focused on technology and making. While there is nothing wrong with that, traditional sciences are just as important. Labs are important. The Annotated Build-It-Yourself Science Laboratory brings the magic of science home again.

Lemon Plum Jam

plumjam-1

The plums on our tree ripened all at once this year! Making this sweet and tart Lemon Plum Jam took care of some of the excess fruit in a tasty way.

Ingredients:

  • 4 cups plum pieces (pits removed, skin still on)
  • 2 whole lemons—large meyers if you can get them—cut into pieces (seeds removed, peel still on)
  • Juice of 2 more lemons
  • 1/2 cup water
  • 4 cups sugar

Heat the plum and lemon pieces, lemon juice and water in a pot on medium, stirring occasionally. After about 15-20 minutes, the fruit should be softening. Macerate the fruit in the pot—a potato masher works well for this. Add the sugar. Stir regularly and cook to the desired consistency. To test consistency, put a spoonful on a plate in the fridge. If it’s too runny after cooling for a few minutes, keep simmering and test again after a few minutes.

Makes about 2-3 pints.

plumjam-2

If you want to can it for longer storage, Ball has a nice introduction to canning (pdf), and additional resources on their website.


Other fruit preserves from the Play with your food archives:

A visit from the LEGOJeep

Lego Jeep at Evil Mad Scientist
Photo by Kevin Mathieu

We had a visit from one of our favorite art cars, the LEGOJeep. Our friend Kevin stopped by to work on some parts to infuse even more LEGO spirit into the Jeep.

Lasering Parts for the Jeep
Photo by Kevin Mathieu

We also had a couple of young visitors stop by to see what we were up to. Above, learning to use the laser cutter and calipers.

Lego Jeep

Very proud of her contribution to the LEGOJeep!

 

 

Linkdump: June 2015