Crookes and other educational deflection tubestuopeek2024-10-23 | Crookes and other educational deflection tubesMagnetron Pulse Switch continuedtuopeek2023-02-06 | This is the second part of an experiment to build a high voltage switch using Silicon carbide MOSFETs forming a high voltage switch. The switch has to be capable of pulsing a magnetron supply at high speeds. Silicon Carbide MOSFETs have low 'on' resistance and have breakdown voltages above 1kV making them suitable. Here we are adding them in series to obtain a breakdown voltage of around 6kV, well above the failure point for a single device. This is still quite a tough ask, as pulses create transients and spike which can be momentary but fatal for semiconductors. The magnetron used is a generic oven type and not designed for pulsing. They can be operated slightly above their ratings but cease to produce any output much below, where they just behave as resistive diodes. Electrically they present themselves as a complicated load resistance with avalanche behaviour depending their supply voltage.
CONTENT: 00:00 - Intro 00:10 - 2nd attempt 01:00 - 3rd design 02:55 - test 1 03:30 - test 2 04:52 - layout 05:53 - last testOven Magnetron Fast Pulsing Switchtuopeek2023-01-03 | Revisiting an old experiment here, pulsing an oven magnetron, but with a different method to control the pulse width. The best solution appears to be in the form of a solid-state switch using Sic MOSFETs. These can be connected in series and switched together. In theory this means the switch breakdown voltage is the sum of the individual MOSFET breakdown voltages. With this arrangement it should be possible to construct a fast switch capable for tens of kV. The video looks at the design issues for switching magnetrons having grounded anodes, casings and waveguides. Unfortunately, the prototype switch fails during initial high voltage testing. One possible cause could have been adjusting the heater voltage as this also adjusts the gate voltage and may have under switched the MOSFETs while exposed to 4.5kV, causing a voltage imbalance on the chain.Transistor number onetuopeek2022-12-23 | 75 years of the transistor To make this short video celebrating 75 years of the transistor, I made this replica of the first demonstrated germanium transistor. The construction has a small piece of germanium sitting on a plate forming the base connection. Two very close gold contacts are on either side of the anvil above. These are pressed into the top surface of the germanium with an adjustable spring load. On testing it didn't demonstrate amplification but I spent less time setting it up. I think it was tricky to get the first one working. Considering how much the world now depends on these it's scarcely celebrated. Can't imagine how many transistors are in the world now, many very old and still in working condition.Nottingham Halloween Gaussfest 2022tuopeek2022-10-31 | Just a few images and video taken at the Halloween Nottingham Gaussfest 2022. Great selection of Tesla Coils, high voltage generators, equipment and coilers. A good fun day and evening event, with some coils working outside. So much more that I didn't get a chance to record. No equipment fails just my Halloween lantern prop got melted in the end.Dekatron countertuopeek2022-09-15 | A short video on an early counting device from the 1950/60s known as a Dekatron. These are similar to Nixi tubes in that they are neon filled but have pins rather than numbers. There is also a cleaver use of gas plasma behaviour to effectively make the device a counter with a clocking frequency.Inside a ECF80 vacuum tubetuopeek2022-08-29 | This is one of two valves used in old VHF TV tuners from the 1960's. Found this one had lost its vacuum so decided to take a look inside. This little valve actually forms a Triode and a Pentode assembly.High voltage and low pressurestuopeek2022-06-30 | Short video showing pressure changing within a Helium - air mixture in a bottle, while subjected to an RF field which can also be adjusted.Bottled lightning (Part 2)tuopeek2022-06-01 | A short added bonus video on the plasma bottle experiment. Now using the UV content from a blue laser pen to trigger the internal breakdown and ignition of the internal plasma.
00:00 – intro 00:12 – laser trigger 01:30 – photoelectric effectBottled lightningtuopeek2022-05-30 | Just a short video on a very big topic while having fun experimenting with some homemade discharge tubes. I'm taking a quick look at some different gas fills, electrodes configurations and excitation methods.
CONTENT: 00:00 - Intro 00:38 - Spectral lamps with two electrodes 02:07 - Single electrode tubes 02:42 - electrodeless tube 02:58 - bottle plasmaHigh voltage transformer from large X-ray supplytuopeek2022-04-09 | These large high voltage x-ray transformers not only generate very high voltages but also have high current capacity. The ratings for peak power can be in the order of x10 kW. This one, I think is, around 35kW with a potential of 150kV. Many smaller x-ray machines have the transformer and tube built into the head assembly. In this larger type, the head and PSU are housed in separate units. This video looks at the transformer and rectifying circuit. The transformer is designed to operate from an 8kHz AC supply normally driven with a half bridge inverter. For testing here, a H-bridge driver is being supplied with up to 30V 30A DC. As these transformers are designed to operate under oil and have a centre tap arrangement it can be difficult to modify them due to the likely hood of breakdown to chassis/ground. The design has similarities to the construction of some later TV flyback HV transformers with HV stages. However, as well as being many time larger, this transformer is full-wave and the core is not gapped as in flyback construction.
CONTENT: 00:00 - Intro 00:58 - Testing 02:45 - Construction 10:20 - Modification 11:50 - Circuit diagram 12:49 - spark testDeaccelerating an electron beamtuopeek2022-02-01 | Another demonstration with this didactic electron beam deflection CRT. This CRT is used for electrostatic and magnetic deflection demonstrations and shows the relationships between the plate potentials or coil currents and degree of deflection. However, in this video, using both electrostatic and magnetic deflection, the electron is being slowed down after its initial acceleration from the electron gun. This demonstrates magnetic field don’t influence stationary electrons. Thanks to youtube.com/c/AnthonyFrancisJones for pointing this out demonstration set-up.Last of the DEC Alpha’stuopeek2022-01-01 | A bit on computer history this time. Although this DS10 computer is badged Compaq it was a Digital Equipment Corporation design (DEC) using it Alpha processors. Compaq took over the DECs PC business in 1998 but it wasn’t long before HP picked up both. The Alpha processor held the speed record for a RISC processor at the time and was used in machines that could support DECs own operating system VMS, but also UNIX and Windows NT. Unlike Microsoft who clamed NT stood for 'New Technology', DEC circles claimed it was the 3 next letters in the alphabet from VMS becoming 'WNT' reflecting the design input from DEC. There is a bonus end to the video on an unusual mouse used by DEC on earlier VAX machines.Magic-Eye indicatortuopeek2021-12-03 | Short video on old indicator tubes from valve equipment. Three common types are shown operating with a low frequency sine wave modulating the grids. Fluorescent coatings are used with in the tube to produce a visual indication for signal level. Had some issues with sound on this video, apologies it's a little worse than usual. The three tubes here are electrically very similar but due to the pin arrangements are not interchangeable.Cold-war dose rate metertuopeek2021-11-01 | This radiation rate meter dates from the cold war and was manufactured in the early 1980’s. They were issued to the Observer Corps and designed for detection of nuclear weapon activity. These only registers high doses of gamma radiation and aren’t of any use for low radiation checking.60kV variable lab-bench power supply project.tuopeek2021-10-03 | Demonstration of a fairly simple high voltage power supply based on components from a dental x-ray head. The object is to create a variable supply capable of +60kV wrt ground and a current capability approaching 10mA. To keep the design light and simple the DC primary supply is directly from rectified mains. Although testing is showing the multiplier is capable of around 90kV with a 350V input. I suspect this will be too high for the wax insulation so may have to remove some stages in the multiplier before I finished.Making a high voltage power supply with parts from an x-ray head.tuopeek2021-09-03 | This video looks at the feasibility of using parts taken from a small X-ray head to recycle into a useful bench variable high voltage supply up to around 70kV. My current bench supply delivers up to 30kV at 500uA. I am looking to more than double both voltage and current using these parts. X-ray supplies tend to have centre tapped outputs giving half negative and positive outputs with respect to ground. This reduces the demands on insulation for the manufacturer but isn’t particularly uses full for experiments.Different kinds of Diodestuopeek2021-08-18 | If I say ‘diode’ you probably think silicon diode but there were others before silicon. Germanium also comes to mind and they still have special uses today. There were also vacuum and metal oxide diodes in common use before silicon became mainstream. This is a short video on the insides of a selenium bridge rectifier package and a brief look at the metal oxide semi-conductor.2nd Generation CD player - Philips CD104tuopeek2021-07-09 | Looking into why this early second generation CD player has superior tracking to more modern units. Although built in 1984 I have kept this compact disk player as it out performs many more modern units, seamlessly coping with marked and damaged disks.ГУ-81М Vacuum Tube Tesla Coiltuopeek2021-06-12 | Enticed by another VTTC this time based around the popular Russian ГУ-81М (GU81M). This seems to be a massively over engineered tube and able to take the hammering Tesla Coils can often give their primary circuits. I am being kind to this one. Although modular in construction, with a Steam-Punk look, I have as usual, crammed all the components in for a small footprint. This limits future modifications to some extent. Check out ‘Tested to Destructions’ video to see what these tubes can be pushed to. Link: youtu.be/8O727kUU7TcTektronics PRISM 3002 Logic Analysertuopeek2021-05-10 | An old Tektronix Logic Analyser isn’t something you need every day but nice to have. This PRISM 3002 model dates from the 1990s. Even though now long in the tooth it is an interesting instrument packed with technology that can still be useful today. The specification for this analyser, with its two GPX acquisition boards is; 160 channels at 200MHz transitional timing, 32channels at 1Ghz conventional timing, 160 channels at 80MHz state. Its own processor board is based around the Motorola 68010 with 4 Mb RAM and 48Mb capacity MFM hard drive. The unit had been working the last time I used it a number of years ago. Thinking it would be interesting to show it working and to look at the construction, I discovered it no longer worked. Research took me to some Diagnostic documentation and a failure scenario, that occurs when the on-board date/time becomes invalid.plugin PVtuopeek2021-04-07 | Plug and play solar was an interesting concept but wasn’t really adopted. This little adapter was an early attempt to make grid linked solar easy and affordable for anyone. I am testing the device here with two old 20W thin film PV panels indoors. A big THANKS for watching , following and subscribing as this short video also mark 10 years of uploads on Tuopeek1.Radiation detectors part IItuopeek2021-02-28 | A continuation video from the last one on photo multiplier tubes. This one looks at a semiconductor alpha particle detector and a Russian ‘pancake’ Geiger-Muller detector. A link to the very useful pulse recorder and analyser (PRA) software used to produce sounds and graphs is given below : gammaspectacular.com/marek/pra/index.htmlTesting a Photo Multiplier Tubetuopeek2021-01-31 | Playing with Photo Multiplier tube here on an external supply of 900V. This tube has a large window and 11 Dynodes making it quite a sensitive. Also include a demonstration of very low energy x-rays being produced at 8.8keV. This was surprising, an acceleration voltage this low it can be found in Oscilloscopes CRTs, whereas old television CRTs use 15kV and 25kV.DIY CRT Oscilloscope project from the 1980stuopeek2020-12-30 | Here's an extra video to finish off the year. This is a bit of nostalgia for me as it was a college project and still a teenager at the time. It was the only way to get an oscilloscope for home use. A few years later I had acquired a proper scope or two and this project was forgotten, stored the attic, until now. The book I used to base the project was ‘How to Build Your Own Solid-State Oscilloscope’ by F.G. Rayer. By any standard this is a very basic service CRO with no real calibration and AC coupling. It still proved useful in basic fault finding at the time.Vintage Electric kWh metertuopeek2020-12-03 | Found this old ‘vintage’ kWh meter in a junk pile looking very sorry for itself and thought it would be worth taking a closer look. This was a common style of kWh meter from the mid-1900s, and is well made. It is a 3-phase example and would have been extra tough for use in an industrial environment. The kWh is an interesting unit as it is commonly referred to in engineering circles but not really recognised in physics, where the Joule is the preferred unit. The Watt being a rate is easily confused, and for energy has to be referred to as a watt/hour to be correct.Deuterium Lamp and Power Supplytuopeek2020-11-09 | Deuterium (D2) is a rare form of hydrogen having a neutron in its nucleus. Often associated with ‘heavy water’ it is also used in these unusual low-pressure arc lamps used in spectroscopy. The lamp is special as it provides a nearly continues spectrum in the Ultra-Violet region from around 180nm – 300nm. This type of broad band emission relates to the molecular nature of the gas and not just the electron level transitions. The D2 gas is at low pressure but runs hotter than in other types of low-pressure spectral lights. The outer envelope is special UV glass to allow the transmission of the wide band UV emissions. The normal running voltage is around 100V with a current of 300mA and requires an ignition anode voltage of about 500V. They are designed for 2000 hours of operation.Travelling Wave Tube Amplifiertuopeek2020-10-27 | Another cathode ray device, the Travelling Wave tube (TWT) is used in microwave communications and radar. Unlike magnetrons and similar to klystrons, it doesn’t create the wave but amplifies it. These linear beam tubes can have output energy in hundreds of kW where as this example has just a 1W output.Neon gone Badtuopeek2020-09-15 | This neon tube was one of my first practise builds. It tested fine but the neon back-fill was not as accurate as I would have liked. It also overheated slightly during ‘burn-in’ which is a clue to the future behaviour of the tube. A light silvering started to show around the electrodes and after a few weeks the tube became difficult to light requiring a higher and higher ‘striking’ voltage, eventually becoming faint and flickering. The glass fluorescence suggested the vacuum was improving. Normally, it’s a struggle to keep a good vacuum with internal ‘out-gassing’ spoiling it, but in this case the tube is removing gas by itself.Television Cathode Ray Tubes (Part 3)tuopeek2020-09-07 | Found this very old television (Mullard MW6/2) CRT in my collection while making the previous CRT video and decided it was interesting enough for an extra short video on it. It is the earliest CRT I have seen with an internal coating of aluminium over the screen.Television Cathode Ray Tube Electron Gun Evolution (Part 2)tuopeek2020-09-02 | Playing with old CRTs always generates lots of questions. I have tried to answer some of these in a series of two videos on the history and construction of common television electron guns. These CRTs all employ electromagnetic defection provided by scan coils or yokes. The videos covers both Black & White and Colour tubes and tried to show how to identify pins on the base when no CRT data sheet can be found. The early colour CRT gun is shown here but Mullard released an excellent film on the manufacturing of this tube, ‘It’s The tube That Makes the Colour’ and it can be seen at: youtu.be/0Qd4IX3wpZk In this second part the parts of an 'in-line' electron gun is dismantled along with some common pin connections. Warning you need to be very interested in electronics and cathode ray tubes to watch these two videos.Television Cathode Ray Tube Electron Gun Evolution (Part 1)tuopeek2020-09-01 | Playing with old CRTs always generates lots of questions. I have tried to answer some of these in a series of two videos on the history and construction of common television electron guns. These CRTs all employ electromagnetic defection provided by scan coils or yokes. Heater voltages are generally 6.3V. The video covers both Black & White and Colour tubes and tried to show how to identify pins on the base when no CRT data sheet can be found. The early colour CRT gun is shown here but Mullard released an excellent film on the manufacturing of this tube, ‘It’s The tube That Makes the Colour’ and it can be seen at: youtu.be/0Qd4IX3wpZk In this first part, the history of electron gun development is covered along with some common pin connections. Warning you need to be very interested in electronics and cathode ray tubes to watch these two videos.Electrode-less Neon tubestuopeek2020-08-06 | This is some homemade gas discharge tubes being tested. These are simple glass tubes with no internal electrodes. The low-pressure gas fills are excited by IF or RF high voltages. Some tubes have fluorescent powder or iodine added. This changes the behaviour of the light emitted, as does changes in voltage and frequency.Striations in low pressure gas dischargetuopeek2020-07-30 | While making and testing some small discharge tubes I spotted this demonstration of striations (light and dark spaces) occurring in tube containing Argon at low-pressure. The discharge tube is being driven from a small high frequency cold cathode fluorescent tube driver taken from a laptop LCD back-light. Touching the tube capacitively loads the circuit and the driver’s frequency changes slightly displaying the resonance.Helium-Neon and Carbon-dioxide laser overviewtuopeek2020-07-19 | There are a number of gas lasers around, but the helium-Neon (He-Ne) and the Carbon-dioxide (CO2) are probably the best known. The He-Ne is now totally obsolete now since semiconductor lasers appeared and the small CO2 may go the same way soon. This is just a quick look at these two lasers operating. All lasers have safety issues but the CO2 laser produces an invisible infra-red beam which is hot enough to melt glass. The beam can be reflected from some surfaces and become a hazard. The voltages used to drive these tubes is very high and care must be taken with the power supplies, cabling and connections.VTTC running on a high voltage microwave oven invertertuopeek2020-07-03 | This is a little experiment to see if my VTTC will run using an inverter microwave oven supply rather than the heavy iron core transformer. As Tesla Coils create electrically noisy environments, I didn’t expect the inverter to function well. Initial tests are promising and I need to do more comparisons. Thanks to ‘Tested to Destruction’ for supplying the inverter. Note: Don’t try anything with these transformers without being fully aware of the risks. Their configuration is unusual(+ve ground), it is easy to make mistakes and end up with a very dangerous circuit.Mid Summer Coil Testtuopeek2020-06-23 | Solstice seems like a good excuse to take the TC out side for a load test. Although still on a Variac almost at full mains supply and building confidence after destroying most of the silicon previously. Also trying out a newly wound secondary coil. Just one scary moment when either the over-current or under voltage tripped but came back in good. The insulator was added to see if corona would a appear on the metal work as there are some sharp corners on it. There are also some fluorescent lights and a neon for added interest.High Voltage Test transformer (Part 2 - Pulse and Thermal Tests)tuopeek2020-06-05 | Just a short additional video on Testing the HV Test Transformer. This video covers two simple tests that prove there are shorted turns internally. The only thing is I still don't know if the problem is in the secondary or primary coils.HV Test Transformertuopeek2020-06-03 | This transformer was used to generate high voltages for an engineering test environment. Disappointingly, it doesn’t seem to reach the voltages I would expect. The output looks likely to be around 100kV, but I have only managed 20kV with excessive primary current. Finally, I have had a chance to investigate this transformer further. I have little information on this transformer and its specification plate has been removed at some point. The video shows some of the testing carried out.Van de Graaff generator testtuopeek2020-05-06 | Short video on a Van de Graaff generator showing how equally charges surfaces repel.
Extra video made possible by lock-down :-)
this video was edited and uploaded using solar generated electricityRover V8 EFI systemtuopeek2020-05-04 | Rover V8 Electronic fuel injection system upgrade for the early Lucas L-Jetronic to the slightly later 14CUX hotwire flow meter system.Dancing Cathode Raystuopeek2020-04-04 | This experiment didn’t go to plan quite as well as I hoped. The CRTs are very easily damaged as they run with high beam currents to generate the intensity required for projection. Normally a CRT will survive all but a steady spot, but these damage with slow scan. A possible solution would be to modulate intensity with speed. Thanks to ‘nord’ for the test sound track more at: youtube.com/channel/UCDxqy40E2N9OE7qdxQ85cgA On the plus side the fly-back transformer easily delivers over 40kV and drive 3 CRTs in parallel.Fault finding on DRSSTCtuopeek2020-03-02 | I think my tesla coil works on the edge of survival, and some experiment don’t help. Typically, inverter problems turn into a bit of fault trail. This issue my DRSS Tesla Coil looks initially looked like an in-rush limiting resistor but this just masked a deeper intermittent fault somewhere inside an IGBT.Acorn BBC (master) computer nostalgiatuopeek2019-12-28 | Saved from a skip many years ago this is an attempt to get this old 8-bit computer working with what I have available. I am using a small LCD monitor which has a good range of syncs and will often display a CGA signal which isn't too far away from the BBC Computers output.small Xenon XBO lamptuopeek2019-11-18 | This is a small Xenon 180W XBO lamp normally used in medical equipment. These are specialist lamps and not related to car headlamp, so called xenon lamps which are actually halide lamps. Although new it wouldn’t work. On investigation it looks like it was connected in reverse bias causing the cathode to be damaged instantly. This has changed the lamp’s operating specifications to the point it wont work. I decided to try and get some life out of it so that I could look at the spectral output. Warning if using head phones: the high voltage spark gapped igniter used in the video produces loud spark.High Voltage PSUtuopeek2019-10-14 | While trying to test an old military CRT, I ended up taking a look inside a couple of high voltage power supplies I use.
I think the CRT shown being tested is a Cossor VCR97 as used in early WWII radar. All the original markings have rubbed off.Unusual vacuum chamber apparatustuopeek2019-09-17 | Some interesting mystery stuff arrived with a high vacuum pump and chamber I acquired recently. Quite a bit of work is needed to get the chamber running but I thought it would be interesting to look at the items included as I haven’t managed to figure out their purpose completely. The electron gun assembly kit could come in handy in some future experiments though.VTTC demo and Plasma Globe teststuopeek2019-08-07 | A bit more Tesla Coil stuff, this month, but this time with a vacuum tube (valve) oscillator type. These are quite simple in design and produce small but quite arcs compared to a SSTC. After a brief walk through and demonstration it gets hooked up to a faulty Plasma ball for some gas pressure investigation. After capturing all the video, the globe imploded on the bench, most likely from the thermal stress and higher vacuum.Tesla Coil Testing (part 3)tuopeek2019-07-09 | This is the third part in my latest Tesla Coil project. It has me persevering with the success and fails of coil modifications. After blowing an IGBT a few new modifications have been made and some tentative testing. It may even be getting somewhere at last.SSTC fix and modificationtuopeek2019-06-08 | Short update on my last SSTC which blew an IGBT module during a test. Although disappointing it gave me the chance for a tear-down and look at the failed silicon.Emission and Absorption of Sodium Lighttuopeek2019-05-06 | The Royal Institution (Ri) released a video on sodium light absorption. I decided to make my own version and show a couple of other absorption and emission effects with a variety of sodium lamps. The Ri video can be seen at: youtu.be/Kn2OyQh6o7U (How is Black Fire Made) This video also marks more than 1000 subscribers. Thank you to everyone that finds these interesting, other than me, and for subscribing.