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The Circlon machine and the pen test.

After seeing a video by Robert Howsare, showing what he calleds ”a drawing apparatus” (built out of two turn tables and some wood), I was fascinated. The urge to find out what the design was capable of, was so great that I decided to build one for myself. Mine is built with two stepper motors instead of turn tables. Stepper motors are not as cool as turn tables, but they do give you the opportunity to control the speed and direction very precisely.

One thing that anyone who as ever built a drawing machine realizes, is that to get quality results you need a quality pen. There are millions of pens out there, but after a little trial and error I realized that rollerball pens or pens with gel ink are the best pen types for my machine. Both rollerball and gel ink pens use a water based ink that is less viscous then the oil based ink used in ballpoint pens. The Circlon machine sometimes move very fast, so the pen has to be able to release enough ink to make solid lines even at high speed. Rollerball and gel ink pens will release ink easier then the ballpoint, so they seem to be the best choice. To once and for all try to find the best pen for the Circlon machine, I bought seven pens from penstore.se and did some testing.

The pens in the pen test are:

Pentel EnerGel
Pilot G-2 07_2
Pilot G-TEC-C 025 2
Pilot G-TEC-C4
Rotring Tikky Rollerpoint
uni-ball eye micro
uni-ball Vision Elite 2


The pens best suited for the drawing machine were the Pentel Energel Deluxe RTX and the Pilot G-2 07. These two pens were the only pens where the line was solid even at very high speeds. For normal hand writing I liked the uni-ball eye micro the best, however all the pens in the test (except the two pilot G-TEC-C models) were great for my style of had writing. Due to the very narrow tips of the G-TEC-C models, the pen has to be held at almost a right angle towards the paper to get good results, and that is not the way I like to write.

I have paid for all the pens used in the test my self and I have no affiliation with the penstore.se.

Pentel Energel Deluxe RTX

The Pentel Energel Deluxe RTX releases a lot of ink, and it does so very quickly. It was the best performer when it came to drawing a continuous line in the drawing machine, regardless of the speed. When left stationary in the drawing machine with the tip out, an ink blot formed around the tip. When it comes to handwriting, it might even be considered a bad ability that that the ink flows so easily. The lines are also a little to thick for my taste.

Pilot G-2 07

Before this pen test, the Pilot G-2 07 was my favorite pen. The one I had ran completely dry while demoing the Circlon machine at  Stockholm Mini Maker Faire. After the G-2 ran out, I switched to a Ballograf ballpoint pen and the results were quite disappointing with ink blotches and more mechanical ware on the paper compared to the gel ink Pilot G-2. The Pilot G-2 was the second best pen to use in the Circlon machine, it produced nice solid lines even at high speed. The only thing that made is slightly inferior to the Pentel Energel Deluxe RTX, was that the line thickness of the G-2 was not as consistent. After trying out all these pens, I now feel that the G-2 releases a little to much ink to be perfect in the machine.

Pilot G-TEC-C25

The Pilot G-TEC-C25 has the thinnest tip of all the pens in the test, and that becomes very evident when you try to write with it. It feels more like you are trying to engrave the paper than writing. You have to hold the tip almost perpendicular to the paper for it to release any ink at all, and that is not my style of writing. When it comes to the Circlon machine, I think it did slightly better then its thicker brother G-TEC-C4 but there are some gaps in the line with the C25 as well.

Pilot G-TEC-C4

While not as thin as the 0.13 mm tip of the C25, the Pilot G-TEC-C4s tip is still to fine for me to write with at a normal angle. This could be a good pen for drawing thin lines with a ruler, but it is not for writing. One use for it would be in the Circlon machine when running very dense patterns that tend to get messy with a thicker tip. However, the fine tip makes it very slow in releasing ink which makes it necessary to run at very slow speeds.

Rotring Tikky Rollerpoint

The Rotring Tikky Rollerpoint has a nice dark black ink which flows very easy. It’s a nice pen to write with but sometimes it feels like the ball at the tip gets a little stuck, this is a very minor thing but I did notice it. At slower speeds I think that this pen could work very well with the Criclon machine, but at high speeds it does not release enough ink to draw a continuous line.

uni-ball eye micro

The uni-ball eye micro is the pen I liked best for writing with. It has a nice black ink and releases enough ink to make nice smooth lines, but not to much to cause ink blots. The tip runs very smoothly against the paper. It was not the best choice to use with the Circlon-machine, but it did ok there as well.

uni-ball Vision Elite

The uni-ball Vision Elite has an ink that is tinted slightly towards grey rather then black. It feels nice to write with, but I preferred the uni-ball eye micro. It did not perform as well as the uni-ball eye micro in the Circlon machine, and there is plenty of gaps in the line where the pen has been moving fast.

Teaching a laser cutter to draw

A few weeks ago I went to the mini maker faire in Stockholm and I wanted to show of the laser. Due to safety concerns I couldn’t run the laser out in public, but to be able to show of the CNC capabilities I built a penholder.

It is a quite simple build made out of wood, some plastic from an old cutting board, a few screws and a 9g servo. The servo is controlled by an Arduino, when the signal that would normally turn the laser diode on is high the servo is set to an angle that pushes the pen against the paper. The design was inspired by the brush holder on the WaterColorBot by Evil Mad Scientist. In their design the pen is lifted up by the servo rather then being pushed down like I did it. I don’t know what is best but it works both ways.

How to repair a Samsung LE40M87BD LCD TV

The other day my TV suddenly turned itself on. I turned it off again, but sure enough after about 30 minutes it was on again. It didn’t take long before the TV was unable to start at all. When I pressed the power button, the TV started to click and the red status LED flashed. I suspected that it didn’t get enough power to start. To me this sounded like some kind problem with the power supply, probably a bad capacitor. Sure enough, after opening the TV, I found three capacitors that were in bad shape, and after replacing them with new ones, the TV works perfectly again!

I suspect that this is a quite common problem, and this solution is probably applicable to more models starting with LE40. However, if you have a model that starts with LE40R*, then this solution might not be enough since there is a memory on the logic board that could have been broken when the capacitors failed. Since it is a quick, cheep and quite easy fix, it might at least be worth to open your ”broken” TV to see if it suffers from the same problem as mine. I payed 5$ for the capacitors, and you can probably get them even cheeper on eBay.


This is a pretty simple repair, and you don’t have to have any great soldering skills, but you do need a few tools and of course new capacitors to replace the broken ones with.


  • Screwdriver, PH2
  • Soldering Iron
  • Solder
  • Solder sucker
  • Wire cutter
  • 3 pcs of 1000uF 16 or 25V electrolytic capacitors

Step 1, open the TV.

Put the TV on a soft surface (like a bed) with the display facing down and remove all screws holding the back together. After all screws have been removed, you should able to lift the back cover right off.

1. back_open

Step 2, look for any bad caps on the power board.

The power board is the white circuit board in the middle of the TV, (the capacitors that were broken on my TV has been marked byd arrows in the picture above). You can tell if the capacitor is broken or not by looking at it. It should have a nice flat top. If the top of the capacitor is bulging, it is broken or damaged. If you are unsure, compare it with the other capacitors around it. They should look the same.

Step 3, Desolder the broken capacitors

Now it is time to remove the broken capacitors! Start by removing the power bard from the TV, unscrew all screws and and disconnect all wires to be able to remove the card from the TV. After removing the card, locate the solder joints for the bad capacitors on the cards backside, the green side. In my case the capacitors were CM811, CM812 and CM817. Use the soldering iron to heat the solder joints, when the solder turns liquid, use the solder sucker to remove the solder. If you have problems melting the existing solder, try adding some new solder on top of the existing solder joints. This might sound counter productive, but when we add more solder we create a bigger surface for the soldering iron to heat and this makes it easier to heat it. Once you have removed as much solder as possible with the solder sucker, you should be able to remove the capacitors by hand. Be a bit careful when you do this, since there is a risk that you will brake the copper conductors on the circuit board if you bend to much. It can help to add some more heat with the soldering iron while bending if you have problems to remove the bad capacitors.

Step 4, Mount the new capacitors

The existing capacitors that broke were 1000uF 10V capacitors. Since they broke, I suspect they were under-dimensioned. There for I replaced them with 1000uF 25V capacitors instead. What is important here is that the capacitor that you use is 1000uF and at least 10V, so anything above 10V is also ok. I would recommend using 1000uF 25V capacitors. I got mine from the local TV-repair shop but you can also easily find them on eBay.

These capacitors are what is called polarized, that means you have to connect them the right way. To see which of the capacitors legs is the anode (+) look at the length of it, the longest leg is the anode (+). Almost all capacitors are also marked with a (-) on the capacitor housing indicating which leg is the cathode (-). Thread the capacitors leg through the holes and make sure the anode is in the hole marked (+) on the circuit board. Now solder the new capacitors in place and clip the legs of the new capacitors close to the board to make sure they don’t cause any short circuits.

Hopefully you will now have a working TV again.