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/0876aa4d-d6a7-4b4e-9e7e-e35381011cd7n%40googlegroups.com.
