Workshop

Yay i did it! I finally got my own electronics workshop.

In this pic it looks a bit lonely and sterile, but its actually pretty cool to work with it. So lets come to its features:
On the left you see a big old CRT screen. Thats because the LCD i wanted to use is broken. So luckily i convinced my parents to not throw away this monitor back then (yes i never throw stuff away that still works, or sell it, because i know i will need it one day).

Behind the screen is the computer. Its a pretty old one. Only has a single core Celeron with 2.66 GHz. With Windows 8.1 it kind of works, but the browser has a hard time rendering websites if the cpu is used by something else... like my oscilloscope :D.

Yes thats right. I have an USB oscilloscope! It sits on the first shelf a bit right to the monitor (on some aluminium foil for shielding from the monitor. Actually that doesnt do anything but safe is safe :P). It cost me 100€ and can measure up to 250 KHz (well 250k samples a second). The special thing about it is, that it has 8 channels. So if i have to measure many things at once, im on the safe side. The downside of this is that the 8 channels are multiplexed, meaning that i only get half the accuracy when i use 2 Channels, and only a third when i use 3.

Next feature: The laboratory power supply sitting right next to the screen (red display). It can supply 0 to 32.3V at 0 to 5.1 Amps (actually 30V at 5A but they added some buffer to make sure it reaches the specified values). Well it can't give you a stable 30V at 5 A (it just cant do 150W output). It only cost 50 € so its okay (Good PSUs are expensive!). If i need Amps i can just get one of my old PC PSUs which then burn up the hood :P.

Lets get to the less technical stuff. Before i made this workshop, there was just the shelf on the bottom with all my crap on it. This was horrible to work with and i got backpain, because its too low to work on it when standing. So i got myself a nice Beechwood plate (250x50x18mm). I put 2 coatings of varnish on it, but i doubt it will hold up very long :P as you see im doing some heavy stuff on there. To raise the height of the working surface i used some 8x8cm pieces of wood that i glued together and screwed onto the plate.

Now for the shelves. Those are 2,80m long and 20cm deep. I can store all my crap on there that i dont need at the moment. If that is full i can still put stuff under the working surface :D. Oh i forgot to mention the outlets. we (my dad and i) placed 3 double outlets on the wall. the outlets can be controlled by a switch on the right (which you can't see in the pic). So when i build a tesla coil and it goes crazy i can use the switch to restore safety :P.

Thats it for the workshop. i can now do some nice electric stuff. I will probably post more entries on my progress. Next up is a controller for the big motor that you see there.

New Amplifier

A few weeks ago my old stereo that i had running every day for hours for over 10 years finally said goodbye. Its probably just a fuse, but it popped during normal usage, so i think its finally time to replace it (i already had to replace the big caps, because they were completely dead). The problem is, stereos cost money, and i dont like to spend too much at once. I got the old one from a fleamarket for 10 bucks, including 2 ceramic speaker boxes! It was an incredibly good deal. Sadly i managed to kill the woofer of one of those boxes (the voice coil detached from the cone). I tried reattaching it, and almost got it working... until i didnt detach it during a soundtest and the coil came loose again =/.

So for the last few weeks i had no audio, except my earbuds, and a smaller speaker that i directly attached to my soundcard. Luckily a friend found a very old amplifier in his attic and gave it to me. Its a 10W/15W 4-Channel amplifier. Of course thats not comparable to the old Stereo with its 250W each channel, but i set it up today and it works :D

As its an old amp, it uses old connections. my stereo hat cinch as inputs and and these clamps for the speaker cables. This one instead has 5 pole connectors for input and those old speaker connectors with the big, flat contanct in the middle. I had several of these speaker connectors in the basement, but i was lacking something that could connect my computer to a 5 pin connector.

For years i only had a mono connection to my stereo, because i had no cable with 3 leads available at the time i got it. But i found a 5 lead cable in the basement that i can use. Now i also had an old 5 pin connector cable around, that i got from a microphone for a big tape recorder. The microphone was essentially a little speaker. This connector had a little transformer inside the plug, which is probably there to protect the microphone from the high voltage from the tape recorder it came with. Also this microphone was mono, but had 4 leads in its cable. So i detached the transformer and resoldered the 4 pin wire to the connector. I used 1 lead for ground (pin 2), 2 pins for stereo play (pins 3 and 5) and one pin for mono record (pin 1). I didnt attach the last lead to my computer, because that made no sense. I just soldered it to the plug because i didnt want it to fly around. Then i soldered the cable of the plug to the 5 lead cable and the 5 lead cable to my stereo cinch cable that i had from my stereo, which i uses to connect my computer to the aux input (i now have 2 free leads in the 5 lead cable, for other uses).

My stereo had a contact switch that switched on a relay to power the stereo, but the old amp has some rotational switch for that. As i plan to use this amp for some time, i dont want to put too much stress on this switch (i switch it on and off at least once a day), so i attached an old lightswitch to the mains cable and put the amps switch in the on position.

I plugged everything together and it works :D

I now only have to put the new cable in the cable duct and everything is finished

Planning how to use the styrofoam cutter

Of course i didnt build the styrofoam cutter just for fun. we want to put styrofoam under our pool as isolation. But our pool is round. I could now go outside and lay out the platters and draw on them where to cut them, or i could use modern technology for this. Of course I used the latter :P

First i opened GIMP and created a new picture measuring 400x400 pixels (pool is 3.66m in diameter and we want a bit of overhang). I then drew a circle spanning the full width of the picture and placed rectangles to cover it. My styrofoam sheets are 0.5m x 1m in size so i used rectangles measuring 50x100 pixels. The result is this:

With this pattern i can propably save 4 or 5 of my 32 styrofoam sheets. Now i have to layout this onto my sheets. And here is the layout:

On the left the white stuff are leftovers. As you see i can save 2 sheets. But i managed to put one piece twice in a sheet, so i save a third one on the other half (wohoo 5 sheets saved!). The whole thing is symmetrical so i have to cut out each piece twice. Thats what im going to do the next days :D

little update: today i cut all the styrofoam sheets and of course i fucked it up and did not save the 5th sheet -.-. But otherwise it worked like a charm :D

MacGyvered styrofoam cutter

Welp its time for my first blogpost.

We are getting a new pool because the old one broke and we wanted to enhance everything (one of those with the one air filled thing on top that floats and hold itself up).

Our old pool cooled down every night to 16°C or maybe less(20°C during day), and only kept temperature during the hottest days in summer, so we decided to put some styrofoam under it. Sadly styrofoam does not come in 4m big circles, so i have to do it myself. There were two options: Cut it with a knife and get it everywhere, or build my own styrofoam cutter.

I always love to tinker with dangerous things, so of course i wanted to build my own cutter. a quick and dirty method would be to weld a knife into a piece of metal so it sticks through, and then heat it from the underside with a gasflame, but first, i suck at welding, and second we dont have a gas outlet (i would have to do that by myself too and thats where my parents would kill me). so i have to find another way.

I like electricity so i tried to follow the example of other styrofoam cutters and wanted to use a heated wire. I have a cheapo lab PSU that i wanted to use first, but it couldnt get the wire hot enough. So i wondered how could i get more power but still be able to control it?

Good thing i always keep all the things because i will need them 10 years later. I have an old 12V motor that can also act as a generator, as it has permanent magnets. So i wanted to use this as a Generator to supply the wire with enough power. Now i have to drive it with something. I salvaged a 230V universal motor from our old broken washing machine (circuit board went up in smoke for some reason, also salvaged the solenoid valves and the little waterpump that were in there). To drive this motor i also got myself a noice 1000W variac. I also mounted it on a piece of wood so i can clamp it to a table because that motor can cause some karnage.

So now i have to connect both motors. First i thought about a beltdrive, because i also kept the belt from the washing machine, but the other motor doesnt has any grooves on its rotor, so the belt would slip of or i had to position both motors in a specific way. And again i could use something that i got a few years back.

For the old pool we purchased a longer hose for the pump because i wanted to use a car cooler to heat the water with a fire, but we didnt want to position this close to the pool. So i cut up a 20cm long piece of it. The hose fits over the rotors of both motors with a gap. To make it fit tighter i cut up an old bike tire tube and pulled some over the rotors until the hose fit tightly. I then secured it on both rotors with hose clamps.

So i also mounted the smaller motor on a piece of wood so i could secure it too (yes i did this after i connected both motors because im stupid and lazy). I clamped both motors to the table and hooked the big one up to my variac. I then put my piece of wire in a hacksaw and connected both sides to cables that lead to the 12V generator.

AAAANNNND We're done. I then let the motor run at about 115V. As the generator was under load it ofc didnt spin that fast, and the hose also did its part to slow things down (its a pretty rigid one). But the wire got hot enough to cut through styrofoam like butter :D.

Now i only have to layout the styrofoam sheets so they cover a circle and then start cutting :D

pics:

The variac with attached outlet:

Big motor with its wiring:

Small motor attached to big motor with hose:

Hacksaw with wire and cables:

Motors and variac in one pic: