Oscilloscope CRT - 8LO29I - how to connect it...? - Page 1
Forum section: electronics / projects

author: MrWifiHifi
author_rank: Regular Contributor
timestamp: May 06, 2022, 02:09:08 pm
content: Hello.I have had this tube for a long time, I would like to build a simple oscilloscope from it in the future, which I could also use as an X-Y display with the possibility of brightness modulation.But I wanted to ask how to properly connect and control this tube, because it is not entirely clear to me where and what voltages there can be, what voltage potential can be between the individual control grids and also what current should flow through them. I also have no idea what max. the frequency can be displayed on it.If anyone already has experience with running oscilloscope CRTs or better yet with this particular screen, I would be very happy to advise me.Thank you in advance for any help.

author: tunk
author_rank: Super Contributor
timestamp: May 06, 2022, 02:56:58 pm
content: No experience with this, but you could try a web-search for this: oscilloscope clock

author: TimNJ
author_rank: Super Contributor
timestamp: May 06, 2022, 03:59:51 pm
content: There is a lot to learn - I'd suggest to take a look at some old television repair/design books from the 1950's and 1960's.I have the below "Fundamentals of Color Television" by William Boyce. I'm sure there are many others like it.

author: strawberry
author_rank: Super Contributor
timestamp: May 06, 2022, 04:24:55 pm
content: Oscilloscope CRT schematichttp://www.emartinka.cz/index.asp?IDKategorie=4&IDClanku=18&Akce=clanek

author: MrWifiHifi
author_rank: Regular Contributor
timestamp: May 06, 2022, 05:15:04 pm
content: Ok, so this is how it can be connected. Is it possible to design the power supply somehow so that the screen is powered from only single voltage not from two?I am also interested in what potentiometers to use for focus and brightness, what voltage they must be rated for. I was still wondering how it would be possible to control the plates for X and Y using transistors? What voltage is required for the deflection plates?I am adding here an oscilloscope schematic, according to which I would like to build it, as well as some voltage converters schematics for power supply for the screen. I would be very happy if you could tell me what I can use from there and what I cannot, or what I can adjust/change.

author: james_s
author_rank: Super Contributor
timestamp: May 06, 2022, 05:17:14 pm
content: Yes it's possible, but it sounds like you are quite a ways from being able to actually do it. This is a potentially dangerous project for a beginner so do be careful. I would suggest starting by looking at the various Scope Clock projects out there.

author: MrWifiHifi
author_rank: Regular Contributor
timestamp: May 06, 2022, 05:32:54 pm
content: Here are schematics.

author: MrWifiHifi
author_rank: Regular Contributor
timestamp: May 06, 2022, 05:42:35 pm
content: Fig.1411 to 1413 show an oscilloscope schematics, X and Y deflection circuits, time base and power supply. Fig.1407 to 1410 show oscilloscope accessories, voltage converters for deflection plates and negative acceleration voltage. Furthermore, there are described the circuits of brightness control and section marking, as well as the circuit for measuring the voltage on the given section.

author: strawberry
author_rank: Super Contributor
timestamp: May 06, 2022, 06:40:03 pm
content: 18V regulated + royer generator and ~ETD49 transformer for all tube supply including deflection (similar to C1-68 ...)cascode deflection amps for better bandwidth (could punch limits)

author: MrWifiHifi
author_rank: Regular Contributor
timestamp: May 06, 2022, 08:25:21 pm
content: I am attaching schematics of amplifiers from 10 and 20MHz oscilloscopes. I suppose there would be some change needed, but which one would be better?I looked at the C1-98, the power supply part looks interesting, but the problem is that there are necessary transformers for which I don't have much material. That's why I rather considered the previously mentioned converters, because they require much fewer transformers.

author: strawberry
author_rank: Super Contributor
timestamp: May 07, 2022, 05:58:13 am
content: 1427 looks easier to build. first two follower stages could be removed.or two back to back 12-230V transformers

author: Terry Bites
author_rank: Super Contributor
timestamp: May 07, 2022, 01:19:14 pm
content: Try thiscrtdata.pdf(236.17 kB - downloaded 77 times.)

author: MrWifiHifi
author_rank: Regular Contributor
timestamp: May 11, 2022, 06:28:37 pm
content: I've seen the datasheet before. I roughly know where the voltages are supposed to be, but I don't know how it should be practically connected.As for the deflection circuits, I decided to use those that have a BF245 input. The second connection with KF521 is up to 20MHz, but it also has a higher voltage for deflection, but for 8LO29I a voltage of about 100V is needed for deflection.

author: jonpaul
author_rank: Super Contributor
timestamp: May 13, 2022, 10:26:11 am
content: See Tektronic Circuit Concepts book for CRT circuits.https://w140.com/tekwiki/wiki/Concepts_SeriesJ

author: Chris56000
author_rank: Frequent Contributor
timestamp: May 15, 2022, 03:37:56 pm
content: Hi!Where those articles Fig 1405 to Fig. 1410 taken from a book or magazine?Can someone provide a link to the magazine (s) so I can download & translate it please?Chris Williams

author: strawberry
author_rank: Super Contributor
timestamp: May 15, 2022, 04:45:23 pm
content: Amaterske Radio 1993 ..month 8?

author: MrWifiHifi
author_rank: Regular Contributor
timestamp: June 03, 2022, 09:18:01 pm
content: Here are all magazines with articles I mentioned previously.https://archive.org/details/amaterske_radio_1987/KP_87/mode/2uphttps://archive.org/details/AmaterskeRadio1982k/Amaterske%20Radio%201982k/mode/2uphttps://archive.org/details/amaterske_radio_1993/93-07/page/n17/mode/2uphttps://archive.org/details/amaterske_radio_1993/93-08/page/n19/mode/2uphttps://archive.org/details/AmaterskeRadio1982k/Amaterske%20Radio%201982-05a/page/n11/mode/2uphttps://archive.org/details/AmaterskeRadio1982k/Amaterske%20Radio%201982-06a/page/n23/mode/2uphttps://archive.org/details/AmaterskeRadio1982k/Amaterske%20Radio%201982-07a/page/n23/mode/2up