Pirani is of not much use in our case, as 1) pirani gauges are useful at atmospheric - low vacuum ranges 2) there is low vaccum gauges already, tightly integrated with Cameca SX100 vacuum logic. It is not possible to use low vacuum range of pirani without modifying logical interface of SX100 vacuum; 3) separate cold cathode and pirani (or other low vac type) are more robust. I mentioned WRG (pirani coupled with cold cathode inside single package
https://www.idealvac.com/Edwards-WRG-Wide-Range-Gauge/pl/7-33-291), as sometimes those are off-shelf available at vacuum shops (applied more widely), where cold cathode type gauges needs to be waited for production as it is produced in small batches, unfortunately. What I would like to get ultimately is Edwards AIM200:
https://www.edwardsvacuum.com/content/dam/brands/edwards-vacuum/edwards-website-assets/scientific-vacuum/documents/datasheets/3601-0753-01-AIM200-Active-Inverted-Magnetron-Gauge-Product-Datasheet-LR.pdfIf they fail to deliver that till I get the functioning interface board, I am going then with this:
https://www.lesker.com/newweb/gauges/kjlc-cold-cathode.cfmEventually shop could lend me temporary the WRG (but I need documentation to be sure it is safe to connect), so I would not be so upset and would wait for AIM200 a bit more. WRG is only a temporary option, and not due to pirani, but due to widely available off-shelf cold cathode gauge.
As for arcing, new generation of gauges prevents this by reducing the high voltage after started - that significantly reduces risk of arching. Albeit we are unlucky with that (had not observed this), In our case we rather have lowered voltage at gauge as our cable is partly leaking.
And mine project aims to be as much as robust and to give possibility to make reliable replacement.
1. All parts are THT, for these reasons:
a) the solder joint inspection can be done with bare eye, and is quite straight-forward
b) easiest way to mitigate RoHS enforced tin whisker and solder embrittlement problems (design uses sockets for DIP8 and DIP14 components, not because replacability, but because then IC components can be NiAuPd plated. In case directly soldering such parts it risks in forming cracking when using PbSn solder (have risk of embrittlement and cracking after some time like few years); Where other passive components (i.e. with pure Sn coating) can be dipped into PbSn solder for whisker protection, doing that with Integrated circuit components (in case of pure Sn plated) is not wise as can be damaged by thermal shock. The Not-green components (with PbSn coating) aimed at space and military are restrictively expensive and are sold in packs, thus (over-)plating passive components and using "green" NiAuPd plated ICs is the optimal solution.
c) Can be easily soldered by less experienced.
2. Aims to work with wide range of gauges (currently to my knowledge at least three vendors, and different models). Post-pandemic market fluctuations had shown how not-wise it is to rely on a single supplier of components.
3. Is not tied to single supplier of components, has alternative integrated circuit models and suppliers for circuit to work near identically.
4. No software or firmware changes - just drop-in replacement - The software or firmware will not notice it is different gauge than Alcatel.
5. You probably had noticed Open Hardware mark on schematics and board? yes, after testing the first prototype I will release it as Open Hardware (probably on github, or other repository) - that means anyone will be able to tailor and keep the design up-to-date with best market-available gauges (OH - is like open software, just for hardware). Anyone can modify and tailor for his needs, order the parts and assemble at-site.