The instructions from The Burroughs kit for the BG12205 is in this thread (I cleaned the original up a bit and it is in the last post) where they use 1W resistors.
https://groups.google.com/g/neonixie-l/c/9QE680EzaTc/m/_LUcA8coBAAJ /Martin On Sunday, 2 November 2025 at 06:46:35 UTC+1 Richard Scales wrote: > Hello and thank you for your pointers - right now, the display seems to be > running evenly and looks good - no significant heat is being generated in > the electronics though presence of a bunch of 5W resistors seems somehow > out of place when the display should only be using mA ! > - Richard > > > On Friday, 31 October 2025 at 23:27:28 UTC Dekatron42 wrote: > >> I've dug through my documents and I've been thinking about that 1M >> resistor in the cathode keep alive electrode and its effect on the driving >> of these tubes and I think it is an error to have it there as, even though >> it will only flow a very low current through it, it will affect the common >> ground point for all of the driving circuits and that will affect the level >> depending on how many bars that are lit up. I've never seen a circuit that >> incorporates that 1M resistor in the keep alive electrode for the cathode >> and thinking about it it looks incorrect. >> >> Please correct me if I am wrong but that is my opinion on how these tubes >> should be driven. >> >> /Martin >> >> On Friday, 31 October 2025 at 13:26:11 UTC+1 leo oel wrote: >> >>> IGT1-203 Self Scan bar graph display >>> >>> https://dotdisplay.blogspot.com/2017/08/igt1-203-self-scan-bar-graph-display.html >>> >>> пятница, 31 октября 2025 г. в 12:27:23 UTC+2, Dekatron42: >>> >>>> There are few professional designs in the audio business and in the >>>> ventilation flow control business who completely skip that extra 68V >>>> supply >>>> - I haven't checked the data-sheet what it says but they don't bother with >>>> that extra voltage. Some designs use a SN75468/9 IC (75469 in case of >>>> CMOS >>>> and 75468 if TTL is used) instead of transistors and no pull-up >>>> resistors, >>>> just hook the 68V signal to the common pin on the SN75468/9. >>>> >>>> For all of the designs I've seen there is not one that uses a 1M >>>> resistor on the keep alive cathode, only on the anode, they all just >>>> ground >>>> the keep alive cathode pin directly. >>>> >>>> Some designs uses a voltage between 50-80V for the 68V voltage. Some >>>> designs uses a voltage doubler/tripler to supply all voltages from a low >>>> voltage AC transformer, so maybe use a switcher with say 62.5V DC output >>>> and the quadruple that to 250V DC if there is the possibility of hooking >>>> into the circuit before rectification/smoothing? >>>> >>>> /Martin >>>> On Friday, 31 October 2025 at 06:57:04 UTC+1 Richard Scales wrote: >>>> >>>>> Does anyone have any experience in driving these panaplex-like >>>>> bargraph displays? >>>>> >>>>> I have some IGT2-203R and am using a well publicised circuit from >>>>> here: >>>>> https://stromrichter-org.translate.goog/attachment.php?aid=4116&_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=en-US&_x_tr_pto=wapp >>>>> >>>>> [image: Pic1.jpg] >>>>> >>>>> I have made various changes, I'm using an Arduino Nano for the >>>>> controller, an HV module for the 245V and I changed out the R2/D2 >>>>> combination for an LR8 HV regulator as I found that R2 was getting a lot >>>>> warmer that I would like. >>>>> >>>>> Now I am looking at the anode supply which is controlled by R8+R18 (I >>>>> am only using one channel so don't have R7/R17. >>>>> >>>>> It seems that when Q8 is off, the Anode is connected to the 245 >>>>> supply via 36K for current limiting purposes - that's all good. When Q8 >>>>> is >>>>> on, then the anode is fed from what is now the voltage divider >>>>> combination >>>>> of R8+R18 (98V) - also good. >>>>> >>>>> However, that combination of 24K+36k is drawing about (245/60)mA - >>>>> 4mA - the power being almost 1W - so they get a little warm. I have over >>>>> specified and used 5W parts. >>>>> >>>>> What I have works just fine, and, in fact I even doubled up on the >>>>> resistors to share the load even further but I wonder if there is >>>>> perhaps >>>>> a better way which might not generate quite so much heat? >>>>> >>>>> It might seem overkill but I could make 98V using another LR8 and then >>>>> use high side drivers to 'switch' between the two (like a couple of Opto >>>>> Couplers or a bunch of 42/92 transistors). >>>>> >>>>> ... or am I being over cautious? >>>>> >>>>> - Richard >>>>> >>>>> -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion, visit https://groups.google.com/d/msgid/neonixie-l/63495f3f-478c-42c8-b3c3-d83cf274f1acn%40googlegroups.com.
