Just adding another cat skin to the list.
If you’re making your own pcb then add a place for a 0.1R resistor at the drain of the output mosfets to take the measurement.
Then once satisfied with your bias setting either short them or remove them.
Some people even leave them in but I personally hate the idea of leaving them in.
If you’re making your own pcb then add a place for a 0.1R resistor at the drain of the output mosfets to take the measurement.
Then once satisfied with your bias setting either short them or remove them.
Some people even leave them in but I personally hate the idea of leaving them in.
Last edited:
Pass DIY Addict
Joined 2000
Paid Member
I've been thinking of making a nice little panel for myself that includes my variac, an integrated dim-bulb tester (bypassable with a switch), followed by an ammeter and voltmeter for just such purposes. This would put everything in one place and eliminate my typical Rube Goldberg approach to this type of task.
@woody, no, it's just poorly drawn because I never cleaned it up after playing with a few different ideas. The resistors are in parallel.
(I've also discovered that I can't find any metal films in 4W either, so they need doubling up again -- at which point there's not much point in showing them that way in SPICE.)
Here's a clearer version:
(I've also discovered that I can't find any metal films in 4W either, so they need doubling up again -- at which point there's not much point in showing them that way in SPICE.)
Here's a clearer version:
Attachments
Consider the Hantek CC65 from eBay. I have one and I am pleased with the results I get from it.
I can certainly imagine other instances where being able to view the waveform would be very useful (such as determining the class A envelope -- assuming the output devices are on flying leads).
I did some Googling and Pico also sells one[1]. Looks like it was made in the same factory, but with slightly higher-spec parts (at least there's a strain relief on the cable, and a metal latch ring on the BNC). A bit more dosh, but maybe better quality control too?
Thanks for the idea, Mark!
Cheers,
Jeff.
[1] https://ie.farnell.com/pico-technology/ta018/current-probe-clamp-60a-oscilloscope/dp/2677035
I'm not so sure on the how but new current clamps such as HoldPeak HP-870K shows DC current range.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
- Home
- Amplifiers
- Pass Labs
- How do you measure bias with no source resistors?