I’ve recently finished with the curve tracer project and will be mounting the PCB in a project box – as I’m going for more of a “portable” design and will be using this as a stand alone device and simply hook up the power supply and oscilloscope as needed.
I’m currently researching “connectors” to hook up all the various wires inside the box for the probe leads, vertical/horizontal/ground for the scope, and also the +- power supply.
I’ve been looking at some styles of “banana” connectors but I’m curious if there would be something better out there and what recommendations you may have? Then I would make external leads for the various probe leads I may want, perhaps some short leads for the scope leads to hook to, and then of course the power leads.
It may also be nice to have a connector that would come in three color variants so I don’t cross any wires!
I think the banana Jack would do the job just fine.
My choice would be the following: if the Differential power supply is external to the curve tracer enclosure I would go for the 4 or 5-pin round connector (same as the one MCL used for the super probe and/or the Ultraprobe) I don’t remember the name for it. for the Vertical and Horizontal lines going to the Oscilloscope, I would use BNC connectors and 50 Ohms coax csble and would only use banana plugs for the testing probes. However to avoid cable clutter and since you have “portability in mind” my best choice ( If I were to do it for myself) would be to use a bigger enclosure to fit an internal power supply using rechargeable Li-Ion 18650 cells or similar. Since the c. tracer doesn’t really take that much current and considering the usage is intermittent (since is a piece of testing equipment) one charge of 18650 cells should last you for months (well depending on usage and the cells’ amperage). But again…the choice is yours to make.
@ovi4 Interesting you mention the 18650 cells – I was thinking about doing that as well today to eliminate some additional wires and not have to depend on an external power supply. I think that is a great idea!
Also going the BNC route would be a cleaner install also. I’m glad I posted here to get some ideas as I was thinking this through!
Thanks for your help!
@bh2024el PS: I would also put a small LED on the front panel as a constant reminder that the unit is switched on so you won’t forget to turn it off and accidentally drain the batteries though 😏
@ovi4 You must have read my mind! 😆
I added that note to my build sheet (a notes document I keep as a “log” of sorts for all projects) to add a switch and a “power on” LED.
I was researching some coax last evening as well, and I’m curious what you would recommend for coax for the BNC leads I’ll be making? RG 174? I’d like something similar to my oscilloscope probes as that is nice and flexible – but I was not able to find any coax specs on that.
I’m thinking LMR400 will be over kill? lol
Thanks for you help as usual!
Using any 50 Ohms variant should be fine since there is no real RF going through them. I use RG174 quite often on projects because of the very same reason (nice and flexible) and it doesn’t break the bank 😉 . Some specs for the RG174 are here in PDF format: https://www.pasternack.com/images/productpdf/rg174a-u.pdf
@ovi4 Thanks for that info.
Concerning the battery power supply, should I be looking at a boost convert of some type to get the required positive and negative voltages? I’d be shooting for +- 15V.
Well, to keep things clean and “noise-free” I would stay well away from boost converters as they are practically noise generators especially when it comes to testing equipment but hey…feel free to do a test comparison first (voltage booster versus no booster) before deciding but just keep in mind that the voltage level is not that critical (in my view). I’ve experimented with a range of voltages (using a proper Dual Linear Bench Power Supply) and somewhere in the range of between 14.5 to 18V worked pretty much the same way with no major differences. My setup uses 16.5V and it works fine with no problem. whatsoever.
Ah yes, I didn’t even think about the noise! Shows what I know! lol
With your setup are you running on 8 18650’s in series to get the needed +- 16.5V?
@bh2024el My setup uses a little mains-powered transformer that I’ve had in my junk box. Because the curve tracer is fitted inside the oscilloscope would have been pointless to try using batteries when the mains power is available as it is used to power up the oscilloscope itself anyway so…no, so I didn’t go with the portable route.