Electronics > Beginners
Choosing a PSU, what should I look for
rstofer:
--- Quote from: Moriambar on February 24, 2019, 08:12:29 pm ---
When I use micros I program them far from the "bench". My old computer got stolen from me and had to buy a new one this year and I'm too scared of that blowing up to keeping it near. So it's "no way José".
To summarize: computer-> as far from the bench as possible. Both because I'm not confident enough and because I do hate pc-driven instrumentation. Perhaps one day I'll buy a cheap ass computer and put it on the bench and if it blows up who cares. But not now!
--- End quote ---
I worry about it too! I primarily use a high end model of the Surface Book. I forget what it cost but it was a bunch! A replacement at Best Buy today is $2900 plus tax so about $3200 out the door (plus the extended warranty for another $279 give or take). So, I have a powered USB hub for driving my projects. On the way by, I get 3 charging ports...
https://www.amazon.com/gp/product/B00VDVCQ84
You can also buy USB isolators and I have a couple but haven't played with them. One problem with the whole electronics thing versus PCs is the fact that we use external supplies. We have a source of power that didn't start with the USB port. Most of my projects do, in fact, use the power from the USB port. In a lot of ways, this is safer than combining USB and wall wart power on the same board. Those boards that have this feature vary widely in how they protect the USB port.
Here is one way to power a breadboard from USB and keep everything on the same power source, Power Bricks:
https://store.digilentinc.com/powerbricks-breadboardable-dual-output-usb-power-supplies/
As with anything, there are limitations. I have a complete set but I haven't been doing any breadboarding. I'll see how it turns out...
I wish they made a +-15V brick for op amp projects! 12V might be enough with modern op amps but not with the older models and a +-10V signal swing.
I don't know of any good way to get a decent Bode' Plot from anything less than a full blown network analyzer without using something like the Analog Discovery 2. I really want a log scale for frequency and I really want the Y axis scaled in dB and degrees and while there are some dubious workarounds on a scope, they aren't Bode' Plots when they're done.
When you want to discuss impedance with your grandson, it's nice to be able to show the Bode' Plot and discuss the break points and roll-off rates with diagrams that are properly scaled and annotated. Even an ME student is going to have to take a course in Circuits. Yes, I'm an evangelist for the AD2.
Moriambar:
--- Quote from: rstofer on February 24, 2019, 09:39:39 pm ---
I worry about it too! I primarily use a high end model of the Surface Book. I forget what it cost but it was a bunch! A replacement at Best Buy today is $2900 plus tax so about $3200 out the door (plus the extended warranty for another $279 give or take). So, I have a powered USB hub for driving my projects. On the way by, I get 3 charging ports...
https://www.amazon.com/gp/product/B00VDVCQ84
You can also buy USB isolators and I have a couple but haven't played with them. One problem with the whole electronics thing versus PCs is the fact that we use external supplies. We have a source of power that didn't start with the USB port. Most of my projects do, in fact, use the power from the USB port. In a lot of ways, this is safer than combining USB and wall wart power on the same board. Those boards that have this feature vary widely in how they protect the USB port.
Here is one way to power a breadboard from USB and keep everything on the same power source, Power Bricks:
https://store.digilentinc.com/powerbricks-breadboardable-dual-output-usb-power-supplies/
As with anything, there are limitations. I have a complete set but I haven't been doing any breadboarding. I'll see how it turns out...
I wish they made a +-15V brick for op amp projects! 12V might be enough with modern op amps but not with the older models and a +-10V signal swing.
--- End quote ---
Thanks for the info, the power bricks surely look rather interesting. I will look to the rest too.
--- Quote ---I don't know of any good way to get a decent Bode' Plot from anything less than a full blown network analyzer without using something like the Analog Discovery 2. I really want a log scale for frequency and I really want the Y axis scaled in dB and degrees and while there are some dubious workarounds on a scope, they aren't Bode' Plots when they're done.
When you want to discuss impedance with your grandson, it's nice to be able to show the Bode' Plot and discuss the break points and roll-off rates with diagrams that are properly scaled and annotated. Even an ME student is going to have to take a course in Circuits. Yes, I'm an evangelist for the AD2.
--- End quote ---
Never had the need of a bode plot actually. I only did a bit around 20 years ago or so in one uni lab, but never again. I repeat: I do basically only digital stuff. Program the arduino and then remove the pc and power it from the psu or something like that (I never use usb + anything else: it's either all via usb or all via psu). Couple of ICs and a couple of mosfets. I never needed an op-amp or a bjt either, true story!
I appreciate your passion about the AD2; I'm sure it's a wonderful product. But for my current needs is basically useless, throwing away 260+$ (plus shipping and tax). Perhaps in the future I will be able to appreciate its power and versatility and buy one of its descendants!
Right now it falls in the "I kinda know what it does, I actually do not know how can people find it useful" category, right with the arb-generators.
james_s:
--- Quote from: Mr. Scram on February 24, 2019, 07:45:10 pm ---
--- Quote from: james_s on February 24, 2019, 06:44:35 pm ---Do I really have to point out that I'm not the only one here who has used gear? Thousands of people buy used gear and for most it works out just fine. Older higher end equipment tends to be very well made.
--- End quote ---
I was talking about your experience with a Chinese unit, not even taking things like confirmation bias into account.
--- End quote ---
Will anybody say with a straight face that low end gear like Rigol, Siglent, etc are anywhere close to the quality of slightly older HP/Agilent/Tektronix gear that probably cost 10x as much when new?
How many cheap Chinese power supplies has Dave shown in his videos that were crap? Some are decent, but I'll take a used HP *any* day over a new hobbyist brand at the same price.
Mr. Scram:
--- Quote from: james_s on February 25, 2019, 07:03:51 am ---Will anybody say with a straight face that low end gear like Rigol, Siglent, etc are anywhere close to the quality of slightly older HP/Agilent/Tektronix gear that probably cost 10x as much when new?
How many cheap Chinese power supplies has Dave shown in his videos that were crap? Some are decent, but I'll take a used HP *any* day over a new hobbyist brand at the same price.
--- End quote ---
Top end brand name equipment has been shown to have defects and issues as well, both when brand new and after years of use. The new Keysight power supplies turned out to have quite a few rather relevant bugs in it and it's not the first time that happened to them. Besides, it's not a new HP versus new Rigol discussion. It's a 20 or 30 year old and often beaten up HP versus brand new Rigol with warranty discussion. What's your cup of tea depends on your needs and wishes, but it's not as clear-cut as you make it seem here. Especially a lot of the HP branded stuff is now getting so old that it really needs to be treated on an as-is basis.
Wolfgang:
... and dont forget RIGOL and maybe others in fact *made* some low-end HP/Agilent/Keysight equipment as OEMs.
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