You Can Have my TIPs When You Pry them from my Cold, Dead Hands

We’ve seen a growing number of posts and recommendations around the net regarding components, specifically transistors. “Don’t use old parts” they cry,  “Go with newer components.”  You can often find these recommendations on Arduino forums. This all came to a head with a page called “Do Not TIP,” which was linked in the Arduino subreddit.  This page belongs to [Tom Jennings], creator of Fidonet, and one of the early authors of what would become Phoenix BIOS. [Tom] and a few others have been calling for everyone to send their old parts to the landfill – not use them, nor gift them to new experimenters. Get them out of the food chain. No offense to [Tom], but we have to disagree. These parts are still perfectly usable for experienced designers, and have a lot to offer new hardware hackers.

TIP is the part number prefix for a series of power transistors created by Texas Instruments.  In fact, “TIP” stands for Texas Instruments Power. The series was originally released in 1969. Yes, that’s right, 1969. Why are we still using parts designed when man first walked on the moon? The same reason people are still using the 555 timer: they’re simple, they’re easily available, they’re robust, and most of all, they get the job done. The TIP series has been used in thousands of classes, tutorials both online and off, and millions of projects over the years. Much of that documentation is already out there on the internet. The TIP series is also out in the distribution channel – they’ve been used for 40 years. Any retail shop that stocks a few electronics parts will have at least one of the TIP series.

The TIP series aren’t always the best transistors for the job. However, for most hobbyist-designed circuits, we don’t need the best performance, nor the best price – we’re going to use the parts we have on hand. There is always room to improve once you get the basic circuit working.

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Get Biohacking with a DIY CO2 Incubator

The [Pelling Lab] have been iterating over their DIY CO2 incubator for a while now, and it looks like there’s a new version in the works.

incubator3

We’ve covered open source Biolab equipment before including incubators but not a CO2 incubator. Incubators allow you to control the temperature and atmosphere in a chamber. The incubator built by the [Pelling Lab] regulates the chambers temperature and CO2 levels allowing them to culture cells under optimal conditions.

While commercial incubators can cost thousands of dollars the [Pelling Lab] used a Styrofoam box, space blanket, and SodaStream tank among other low cost parts. The most expensive component was a CO2 sensor which cost $230. The rig uses an Arduino for feedback and control. With a total BOM cost of $350 their solution is cost effective, and provides an open platform for further development.

The original write up is full of useful information, but recent tweets suggest a new and improved version is on the way and we look forward to hearing more about this exciting DIYBio project!

Solenoid motor from a VCR head

Here’s a solenoid motor you can build from a VCR head and some common components. It uses an LED and a light sensor, paired with an LM311 comparator to manage the switching of the motor. As the head turns, the LED shines on the sensor through a hole and triggers a TIP120 transistor to turn on the motor during the power stroke. Once the beam of light is broken, the transistor turns off the motor and the momentum carries it through its revolution until the next power stroke is activated.

We often say that “why” is the wrong question. [Bd5940] must feel the same way because he ends the video by saying: “it has no use, but definitely a conversation piece”. Yep, we’ve seen that before.

[Thanks James]

Giving an old arm new life

[Jarek] found a non-functional robotic arm sitting around and wanted to get it working again. By adding a few custom boards to an Arduino he managed to do just that.

The arm is driven by six stepper motors, each having four control wires. To handle all of these [Jarek] used TIP120 transistors to protect the controller. This still leaves the problem of 24 control wires to connect. By using a couple of 74HC4514 demultiplex chips he cut that number down to just 8 Arduino control pins. He completed the project by interfacing an original Playstation controller as the input device.

Source code for the project is available for download but we didn’t see a schematic for his setup. This shouldn’t be a problem as the low parts count should mean the datasheets for the transistors and demultiplexers are all you really need.