Oscilloscope homebrew pt 4: how to make the CRT working. Dem. & Schem. and key information B7S2 tube скачать в хорошем качестве

Oscilloscope homebrew pt 4: how to make the CRT working. Dem. & Schem. and key information B7S2 tube

Please read the description first and watch the video for the “disclaimer”. Part 4 of making a very simple oscilloscope, for measuring purposes. Demo of the pract. circuit (pt 5, doing a test, 5 dec. 2025, comparing 2 frequencies, is here    • Oscilloscope homebrew pt. 5: first practic...   Vid of 10 dec 2025 is here:    • Oscilloscope homebrew pt 7: about the hor....   You can use the sensitivity of the vertical & horizontal plates to show electric phenomenon, be it an oscillation or a relation between 2 voltages/frequencies. Idea based on a book of circa 1938. Title: “Radio Laboratory Handbook, by M.G. Scroggie, B.Sc, A.M.I.E.E. Consulting radio engineer, issued by “The Wireless World”, ILIFFE & SONS Ltd, Dorset House, Stamford Street, London, S.E.I. around 1938. In the video’s (this and the earlier) my idea was that the book was from 1942. I could be wrong regarding this… But: this is applied physics, and these electric/electronic laws stay valid. The video shows key things you need to know to make a CRT (Cathode Ray Tube) with electrostatic deflection working. Say: such a tube for 1000 V or 800 V anode voltage. 1. The HSP unit/generator (here: via a flyback transformer on say 8 KC) gives out a high AC voltage. In the range of 800-1000 V AC (or lower). Kind of sine wave or another not perfect waveform: that does not matter much. The AC out on 8 KC-10 KC (frequency depends somewhat on the voltage of the transistor flyback generator) is multiplied by 3 in the tripler diode circuit (schematic) & rectified (!) & smoothed (via the caps) to a high Voltage DC. Current goes down, Voltage goes up, Watts/power in-out stay ca. the same. 2. Due to the “load” (= the voltage divider of a few 1 Mega Ohm resistors in a row that supplies the CRT with different necessary voltages, brightness, focus, etc, watch the schematic in the video) the DC output voltage drops to (say) 800 Volt or 900 Volt. 3. In the end we have only a few milliamps at such a high DC voltage. Say 2 mA, that means: 2 mA x 800 Volt = 1,6 Watt or 3 mA = 2,4 Watt of energy, perhaps somewhat more, but enough to make the CRT tube work. “Work” means a bright dot on the CRT screen & light on the screen of the CRT. In fact this is simple. 4. Study the datasheet of your CRT tube for the pin connections. The Cathode is connected to the (-) of the HSP generator, but: 5. The brightness electrode (they say “grid”, in fact it is a small tube) needs to be (can be) made more negative than the Cathode, because in that way (= more negative) it can repell the beam of (negative) electrons, sent out to screen. The Anode is (+) and connected to “earth” (say: 0 or zero). The (-) of the HV generator (working on say 8-14 Volt DC) is also connected to that same “earth/ground”. So in fact the “ground” of the scope circuit is “null”, anyway. 6. For a first test: do not connect that brightness grid, leave the wire of it free to it in the air. When it does not get the right voltage the screen will be dark, even when everything in your circuit is OK (!....). Later: solder a 1 M resistor to it and “probe” that electrode in the circuit 7. Grid 9 is the so called “accelleration electrode”. It accellerates the flow of electrons out of the cathode (-) to the screen, it is thus positive. Sometimes this accelleration electrode (they call it also “grid”) needs a separate higher (+) voltage, but in this case I have directly connected it to the anode (+) on say 800 V or 900 V. So they both work together to attract the (-) electron beam to hit the CRT screen. Kind of issue: the hor. deflection is modulated by the 8 KC of the HV generator. It is not a big issue here. When I switch the HV generator “off” the electrolytics hold enough charge to get a perfect horizontal line on the screen during (say) 30 seconds. Plate sensitivity goes up, if so. First video (21 November 2025) is here    • Electrostatic Cathode Ray Tube B7S2 from E...   Second video 25 november 2025 video is here    • Oscilloscope homebrew pt 2 : a first basic...   Third video 28 November 2025 is here    • Oscilloscope homebrew pt 3 (to test electr...   My You Tube channel trailer is here:    • Radiofun232 on YouTube, find working & tes...   Type there the keywords that you like (e.g. radio/audio/amplifiers/test/filter/) in the “looking glass” = search function” and give “enter”. Via that you can find specific video’s (under the say 1600 published). Via keywords like ”audio”, “radio”, “amplifier”, “filter”, “Shortwave”, “transistor”, “FET”, “oscillator”, “generator”, “switch”, “schmitt trigger” etc; so the electronic subject you are interested in. My books about electronics & analog radio technology are available via the website of "LULU”, search for author “Ko Tilman” there. Or https://www.lulu.com/search?adult_aud... Upload 2 December 2025