Stijn Coenen

Most commented posts

  1. 3D Printer UV Curing Device — 6 comments
  2. Resistor Decade Box — 6 comments
  3. 12V 25A PowerSupply — 3 comments
  4. Dust extraction – Part 1: Valves — 3 comments
  5. Audio Spectrum Analyzer — 2 comments

Author's posts

Radio flea market Bladel 2019

Today there was a Radio flea market in Bladel. I did not see much interesting stuff, so I bought very little.

What I bought:

  • Denon DCD-595 Cd player (that turned out to be defect)
  • DVD drive

Update:

The fault on the CD player was that the CD did not started to turn. After some searching I found out that this was caused by the player not seeing the CD. The lens looked pretty dirty, after cleaning with a cotton swab and some isopropanol I was left with 2 things. A very dirty cotton swab and a working CD player.

Speakon Wall Connectors + Setup

For my living room I needed some speaker connectors in the walls. The power sockets I have are from the brand Niko, so I wanted the speaker connectors in the same look. However I did not like the look of those that are available, and therefore I made my own.

The base is made with a blind panel from Niko (122-76901).

In the center panel I drilled a hole with a step drill, and glued a 4pin speakon connector in the back of the panel:

At the amplifier I used an 8 pin connector. This one I did use screws since the force on the connector will be higher:

Installed:

For the wiring I did a trick to have the speakers always wired correctly when the TV is moved. In the living room I have 3 positions I wanted to be able to place the TV.
Blue = TV; Black = speakers

In each setup I just want to plug the amp into the 8pin speakon and have the signals go to the correct speaker for that setup. This is done with some clever wiring. I gave each 8pin connector a number and each 4pin a letter:

This makes the connections this way:
Connector 1 Pin 1-2 -> Connector C
Connector 1 Pin 3-4 -> Connector D
Connector 1 Pin 5-6- > Connector A
Connector 1 Pin 7-8 -> Connector B
Connector 2 Pin 1-2 -> Connector E
Connector 2 Pin 3-4 -> Connector A & F
Connector 2 Pin 5-6- > Connector D &  G
Connector 2 Pin 7-8 -> Connector C & H

12V 25A PowerSupply

To test my LED Stair Lighting Controller boards I needed a 12V power supply that can deliver a lot of current. For this I chose a SP-320-12 from meanwell. However with the screw terminals it is not easy to use on a lab bench, also there is no display to monitor the output current. Therefore I build an enclosure around the PSU, and added a volt and ampere meter.

The meter I chose was a cheap one from AliExpress: DC 0-100V 30A 50A Dual Digital Voltmeter Ammeter Panel with DC 50A/75mV Shunt LED Red Display

 

Everything mounted in the enclosure (Hammond 1598JSGYPBK):

To limit the voltage drop of the wiring I used a lot of wires in parallel, and braided them to keep them close together:

Front panel connections:

The banana connectors are special ones that can handle 25A. (Red: Farnell 1698956 and Black: Farnell 1698957). Standard ones would probably melt in this use case.

In the back of the enclosure I have made some holes for the air to get in the enclosure, on top of the fan of the PSU I made a air duct to the top of the enclosure. In the top lid I made holes for the airflow to exit.

Front-panel:

Rapid CSN140 Electric Stapler Battery repair (B311 Battery)

I have a electric stapler that works with a battery. This battery became bad some time ago, after doing a lot of searching for a replacement battery.  I found none. I did not even find a reference to the battery. So time to fix it myself.

The battery Rapid Model B311:

The end of the battery pack is clicked into the bottom and can be taken apart by jamming a screwdriver in the seem:

Then this pack came out of the enclosure:

These are 3x 4/5 Sub-C 1100mA cells. To replace them I found N-1250SCRL cells from Panasonic at Reichelt. These cells have tabs attached that can be used to connect them.

For the positive terminal of the pack the tab welded to the cell can be used.  Between the cells I used solder to connect them together.

For the negative terminal the connections in between the cells are in the way, so I had to cut this bar and replace it by a wire.

Connection of the wire to the bottom:

This arrangement just barely fits inside the battery enclosure, when inserting make sure nothing is or can short circuit.

The last step is to reattach the end cap. It does not click in place anymore, so I used glue to attach it again.

And then the big question: Does it work? Yes it works:

Going green (2)

In 2012 we put solar panels on the roof at my parents house. Link to the blog post. Now I have my own house it was time to put up my own panels. I chose again for bisol panels, this time 12x “Bisol Premium Bmo 320wp Full Black Mono” with a SMA STP 3.0-3AV-40 inverter.  Last time Elcubi did a great job, so I decided to also let them do this install.

Pictures:

The panels installed:

The inverter:

The power the installation produces can be looked at here:

Soldering Workbench

In my new workshop I needed a workbench. The one from the old shop was wallmount and too small. This gave me 2 options: buy a workbench or build a workbench. After a lot of searching I did not find what I was searching for.  It was either the wrong size, or too expensive or both. So the only option left was to build it myself.

First I made a drawing of how I want to build the frame:

To start the project I harvested the ugly ceiling trees that where in my living room.

I used a table saw to saw of 3 sides of the beams to clean them of glue and make the corners square. This gave me these beams:

To connect them together I used mortise and tenon connections in combination with wood glue.

Test without glue:

After this I could glue them together one section at the time beceause I did not have enough clamps to do more at once.

Section1:

Section 2:

Section 3:

Section 4:

Test fit without glue of the front part:

Side piece glued:

Complete desk glued up:

Primer painted:

Painted Blue:

Time to make the desktop from MDF, also I installed the racks for the shelves:

Desk in place:

After a few weeks I came across an ad of a free desk frame with steel drawers. I dismantled the drawers and painted them black. These are now installed underneath the desk: (don’t mind the mess, the desk is in use for some time now).

On the next part I will show the LED desk lighting.

Solar logging update

I was not really happy with the logging of the SMA solar inverter. The site was always a few hours behind and the graphs are averages, so I do not realty trust the data. I searched a bit on the internet and found SBFspot. This program runs on a raspberry pi and reads out the inverter and sends the data to PVoutput.

I had an old V1 raspberry pi 1b laying arround. For 99% of the stuf it is too slow, but for this is was perfect. I installed it in my network rack. To save a RJ45 connection on the switch I added an usb network interface to the pi. This way it could be set “in series” with the cable.

The enclosure is one I 3d printed myself. At first I was searching for a din rail enclosure for the pi, but I could not find anything for the old version. Luckily I found these STL files.


The uploaded measurments can be found here:
Today:

Overview last few days:

https://pvoutput.org/intraday.jsp?id=89092&sid=78959

Soldering Workbench Lighting

In the previous part I described how I made my soldering workbench. The part that was still missing was the lighting. For this I first wanted to buy a standard solution, but could not find anything that was fully to my taste.  So time to make something myself.

To mount the light it was easiest to use the same system as the shelves. I used 2 hooks, shortened them and put an aluminium U channel in between.

In this U channel I placed a LED strip that is connected to my desks 12V power supply.

3D Printer UV Curing Device

Some time ago I bought another 3D printer, this time one that uses resin to print. However after printing the parts are not full strength yet. To solve this the parts need to be put in UV light. This can be done outside in the sun or in an UV curing device. Since the sun does not always shine when I’m printing I decided I need a UV curing device.
I did some research on this, but only saw devices that where either much too expensive, or the quality too low or very unpractical. At this time I was thinking why not convert an old microwave oven. It has a rotating disk to put the prints on, it has a timer and it is nice and enclosed.

After asking around I got a defective microwave oven. The tube was defect. However this does not matter for my use-case since I replaced the MOT and tube with a LED driver and UV LEDs.

Now in theory it should already work, but I wanted to make it more custom. I saw that the driver board contained an old PIC16C65B microcontroller. This is a one time programmable, so I replaced it with an (also old) PIC16F877A. Now the timer can be equipped with custom firmware.

Only now the difficult part started. The pins that go to the 7 segment displays do not only drive the displays, they also read out the switches. This took a lot of searching and reverse engineering of the circuit board. I do not have a full schematic off it since I only did what was needed. But I did make a sketch to make this more clear:

The code I wrote for the microcontroller:

The result: