Monthly Archives: April 2018

Automatic Door for the Cat – with HC-SR501 motion detector, without arduino

Even complex project can be done without an arduino. I built an automated door with two HC-SR501 infrared motion detectors.

I use a linear actuator to open the door. This one is from Aliexpress, like everything else, and has limit switches. That means when it reaches either end, it just stops.
In addition, two infrared motion detectors are used, which do not even cost one euro in China. The links are in the description.
We also need a relay with a double changeover switch, an NPN transistor, a diode, and a resistor.
Because the output signal of the motion detectors is not powerful enough to switch the relay, we use the transistor as an amplifier.
The diode is required to protect the rest of the electronics from voltage spikes produced by the relay.
On the switching side, the relay is also connected with plus and minus. In idle mode, the voltage is connected to the last two pins.
If one of the motion detectors detects a movement and outputs a voltage, the relay switches on and the voltage is applied to the other output pins. If we connect them crossed with the last pins, the polarity is reversed and the linear motor runs in the other direction until it stops at the end stop. Continue reading Automatic Door for the Cat – with HC-SR501 motion detector, without arduino

MM: 3D-Printed Universal Paint Adaptor for Nail Polish Shaker

This is the start of a new series: I am going to publish very short videos on Mondays. Not every Monday, but every now and then. In this episode:

3D printed Adaptor for a nail polish shaker to shake modelling acrylic paint, airbrush colors and whatever might need shaking.

The two parts of the adapter are being connected with the springs that are included with the nail polish shaker. The adapter is then being inserted into the ring on the device, because of it’s “wings” it won’t fall out. Happy shhaking!

The STL file is here for donwnloading.

This is the nail polish shaker on,

DIY Salamander / Beefer / Overhead broiler for 35,-€

For the hefty price tag of at least 800 Euros you can buy exotic gas grills like the O F B – Over Fired Boiler – from Otte Wilde or the Beefer. Both of them produce an immense heat that comes only from the top. In the professional kitchen, this is known as a salamander or an overhead broiler. Now I’m sure that these are great products, but they are mostly for steaks, and you need to cook quite a lot of them to justify the expense. But  if you look closely at the beefer, you find a heating element that looks very similar to the one in this gas heater that you can buy for less than 35,- Euros. Maybe we can grill with that just as good? Let’s find out!

Such a gas heater is available for less than 35 euros:

And quite conveniently, there’s even a grill grid included: The protective grate in front of it. We need to get our food as close to the heating element as possible. The edge of the heater is in the way, so it has to go. By the way, if you want to do this, please do it at your own risk, I don’t take over any liability. But we only fiddling with combustible gas under high pressure, what could possibly go wrong?

The grill grid is removed. Now I’m building a foundation out of some stones that were lying around here. Fits. Let’s give it a try. I got myself some beef steaks.

After about a minute, the steak is turned around.

I’ve been experimenting with the distance. Because the grill grate is not adjustable, I simply put some spacers under the heater.

Down below, the first steak is heated to the right core temperature.

It takes some practise, and a proper casing might be helpful, but all in all I am pretty happy with the result.

Better Than a Ring Light – DIY Logo Light

A ring light is so 2017! Everyone has it, and it makes you look like a husky. How about a logo light?

First I need my logo on a piece of plywood. I simply printed it out on 6 sheets of paper. But marking would have worked in the same way. How big? This depends on the desired distance, but it can’t hurt to make it really big. My logo is approx. 60x 80 cm in size, and in the opening credits I am only one arm’s length away from it. I stick my sheets together and add the missing bits of the contour on the margins. Then I cut out the logo. I stick it to the plywood board with a glue stick.

Now an LED strip is used. When you buy an led strip for photography or video purposes, look for a high CRI value (color rendering index). It should be 80 or above.
If you are going to use it alongside other lighting equipment, I would suggest that you match the color temperature. I use 4000k for all my lights.

Compare these LED-Strips:*****

There are special bendable LED strips, but normal strips can also be guided around curves if you fold them a little.

The LED strips can be cut at the marks – with particularly beautiful scissors. I try to cover the logo as evenly as possible with the LED strips. The direction doesn’t matter.

There are soldering points on the LED strips at regular intervals. All strips are connected in parallel. It doesn’t matter where, as long as it’s plus to plus and minus to minus. To connect several pieces with one cable, I like to cut only the insulation. Then pull the insulation apart a little so that the bare copper is exposed and I can solder it on. Maybe I should have been more careful about the polarity though.

After everything is connected, I secure the LED strips with hot glue, I don’t really trust the adhesive layer of the strip.

Now I need cardboard strips with a width of approx. 3.5mm. It doesn’t really matter, but it helps when they are straight and all the same width. I just took a strip of wood as a measure.

Now may be a good time to saw out the hole through which the camera is supposed to look later.

Now I glue the cardboard strips along the whole contour of the logo.

So that the individual LEDs are no longer visible, we need a diffuser. I use tracing paper. This is glued to the edge of the cardboard contours with hot glue.

Now I build a simple bracket.

The connecting plate is screwed between camera and tripod quick mount plate.

And the plywood with the logo is glued on with plenty of hot glue. I can’t screw it on, I should have done that before gluing on the tracing paper.

The result works just as a ring light, only that the camera picks up the reflection of the logo instead of a boring old ring. Try it out!