New stuff was found in trash, so salvaged power amplifier from old tape recorder. It is made with with dual EL84 (6BQ5, 6П14П) tubes.
One funny thing about this PCB. The tubes and most of components are made same year and same month as I was born. So they are as old as I am. 🙂
Also, I break apart few old TVs…
… and removed nice set of power pentodes: 6П36С, 6П44С, 6П45С. They are quite powerful, and it is possible to build some audio tube amps from them. Or radio transmitter!
Sometimes I need small high voltage power supply for my projects. And I don’t want to make special transformers. And I don’t want to use special chips for it. In internet I found very simple circuit diagram for classical step-up converter. It is base on very common 555 timer. The coil used in this schematics is bought in the shop.
Here is the schematics:
Press for bigger image, for printing.
Some comments about this circuit diagram: I needed about 200V DC. During tuning I saw voltages going from Vin up to the voltage dangerous for diode, capacitor and mosfet. You only need to turn trimmer.
Theoretical values are printed in this circuit diagram, but during constructed I didn’t managed to collect exact values and used components from my spare part box.
So here is comments about replacement of components: First of all, T1 is MPSA42. Why author used high voltage transistor? Maybe he had lots of them. I don’t. The voltage here is only going to such level what 555 timer can handle- up to 18V. So I used more common transistor from computer power supply. It is C945 (50V, 0.1A, npn)
C9 capacitor is 100pF. C9 and R37 is typical snubber circuit, it filters out parasitic high frequency oscillations.
Trimmer R40 is 10K, R38- 470K. Diode D1 from old AT PSU, fast, high voltage diode FR154. L1 is from local hobby shop. They didn’t find any 100μH @ 1A, so I put 150μH.
For my power, I didn’t need to put cooling radiator on Q1. Be careful, this device can shock you.
My brother presented me old radio tube datasheet book. In his Antique Shop you can find interesting stuff and for electronics hobbyist. Also he gave me very old radio tubes dated 1920…1930 years! With very strange base connectors and heating voltages.
This book was printed in 1958, in Leipzig. I have only the first volume, but all popular tubes are in the first book. The datasheet book (radio valve handbook) is in three language: German, English and Russian.
I like how tube is called in German language: Röhren, I think, I need to pronounce this word like: “Rioren” 🙂 (in Lithuanian transcription)
There are 549 pages in this, half-sized pocket book. Very good quality of the print. But there are errors in this book. Classical error in soviet tube 6Ð2П , pinout is printed like western 12AX7, that “screen” contact is connected to the middle of the heater… Also in replacement table (equivalents table) I didn’t see the note, that these tubes are using different heating voltage.
I found magic eye tube in my closet. It was removed from sold old radio. This tubes were used in old radio units to indicate fine tuning of radio station. In old tape recorders such tubes indicated recording level. I decided to put this lamp into my tube audio amplifier to look it “cooler”.
Here is the result.
This image is borrowed image from the internet. Here you can see the beam wider.
I used schematics looking something like in the left part of the image. But this circuit works like oscilloscope and it is not very nice. Better result maybe will be achieved using right side circuit. The detect and capacitor will filter out the high frequency signal, leaving only the bass. Just select the 0.1 capacitor according you needed indication speed.
The tube is old soviet Russian 6Е1П or western tube EM80.
In eBay I bough quite powerful Peltiers (TEC, Thermo-Electric Cooler) unit. According to description it is “TEC cooler – Thermal Enterprises model CP1-12726”.
Specifications:
Model CP1-12726
50mm x 50mm x 3.64mm
245 – 320 Watts of cooling power
Operates from 0-15 volts DC and 0-26 amps
Operates from -60 deg C to +180 deg C
Each device is fully inspected and tested
Fitted with 6-inch insulated leads
Perimeter sealed for moisture protection
I don’t know the efficiency of such device, but let’s hope, that at least 10% from its 200W can be used for cooling.
This unit is about as twice as big as my older TEC unit. For hot side I’ll used big Pentium 4 cooler, and the cold side will be small chamber. Now I need to find quite powerful power supply for this device. I need some PSU with feedback, as I need to adjust temperature.
Recently I found plugin for CadSoft Eagle PCB software. Together with freeware ray-tracing software POV-Ray it produces 3D images of PCB boards. It looks like nice illustrations for PCB assemblage instructions. You can see how your board must look like. Also, you can see proper colors of resistors…
Thermoregulated fan control board.
3D library is not full. So these generated boards are missing of components. In this image, you can see, that one power transistor and trimmer are missing.
Just few experiments in Mythbusters style. It is funny experiments with short circuits, high currents, flames and fumes. The voltage is lowered, but current is more than 200A.
The test device schematics looks like this: welding transformer with fuse and thermal protection on high voltage side. On lower side are rectifier, capacitor, voltmeter and shunt to measure current. The shunt is too weak for these experiments- the current is more than 200A.
The “schematics” before experiment:
The victim- 4 square mm copper wire with PVC isolation (~AWG 10…12).
This experiment is unfinished, as the copper wire didn’t melted- the automatic fuse box triggered and disconnected mains. This means, that the current in 230V side was much more than 25A for a long time.
Here is short movie of the experiment: XVid, 670kb. With sound. take a note how wires jumps from magnetic flux caused by high current.
Next experiment with thinner wire. It is about 1 square millimeter solid copper wire (AWG 16) with triple insulation. This special insulation is with filler to stop fire.
The wire melted near connector. The short movie of the experiment: XVid, 670kb. Highly recommended to see the movie with sound.
Ant the last experiment in this day. This is standard tape recorder’s mains cable. With power rating printed on the connector: 230V, 2,5A.
Interesting fact, that short time before destruction, this cable managed to pass 70A current…
Movie of the last experiment: XVid, 670kb, sound is mandatory for this movie. You must feel the power of the blast.
System: Windows XP Pro SP2, P4, PCIe system, Radeon X700 with dual output.
Image on single monitor. Please remember the image ratio.
When I move image to the left and the bigger part of the window is in the left monitor.
And I move the windows to the right. As soon, as bigger part of the windows is on right monitor, image jumps. But again, the image is squeezed.
The images are from DScaler, with overlay video. Something same is from media player too.
That’s me!
Do you notice spot on the roof. Why german make so low cars…
Here is flowers at my workplace.
I watter then twice during winter. On summer time all flowers are placed outside and must feed by themselves. All the cactus’s blossom regularly.
Our toy room has new items:
New set of step drills. On the right- older two, on the left- newcomers.
Chain saw- there will be less trees in our yard.
Electric jigsaw- for our new designs.
Pressure washer- maybe I’ll clean my car.
