Power Supply for Home lab?

I've designed and built many power supplies in my lifetime and if you want something simple that's premade then e14 has reasonably priced adjustable and programmable power supplies.

The Tenma  72-253572-2535 is a good start with both Constant Voltage and Constant Current modes

With both modes available it is very easy to use it to test LEDs.

Another handy tool to have is an accompanying DC load unit as this will enable you to properly test power supplies and batteries)

LOOkatu .. I'm going to build it myself.. MAKE IT MYSELF..
Thanks COMPACT

mudz

you connect mainly  through ethernet to the host, all the apps are web based so in that regard it is isolated due to the transformer in the ethernet physical layer connector circuit

there are a couple of USB ports too but they are not isolated and not normally used for the apps like Scope, Spectrum and LCR

@Fred,

I've only just noticed your post - I'm afraid that I'm much too busy with bread and butter work at the moment to even play with my own pet projects so I couldn't get involved in something else as well.

Good luck with the scheme and I'm almost always able to chat about details - just not free to put any serious effort in.

MK

Thx for the pre-evaluation of the Red Pitaya. It looks Great. I have a few Simply Q's if you can indulge me:

Q1; For 3X the price of a BitScope, this provides more than 3X the Options/ Capability(es) . Do you agree?

Q2. The Red Pitaya is Linux-based, while the User Interface is Web-Based, so the "Controlling-function-(virtual)-Knobs/Display" can be on (let's say) a Windows PC/Laptop?

Q3. The uSD Card on the Red Pitaya (RedP) Determines the Functionality of the RedP, much like the uSD card in a RaspPi? Debian O/S  for a RaspP PC. Minibian for a RaspPi Controller (using GPIO Pins)

Q4. Is the RedP available in the USA? Somebody said "470" Dollars?

Q5. Is the USB Port on the RedP a USB-"B"  Female Receptacle? Another words in original USB parlance: PC/Laptop = Computer;; RedP = Device.

Thx.

USCDADNYC (NY NY USA)

To Peter Oakes:

Updated Q5: Saw a few youtube videos on the Red Pitaya (Acronym "RedP" OK?. What acronym does the community use?). Saw that the Full-Size USB Connector(on RedP)  is a Full Size Female Receptacle -A..

Q5A. This being the case, Maybe? IF you connect both PC/Laptop to a USB Hub then you can use (2) Male-Female USB-A Cables? Possible to do it this way?

Q5B: What about a Full Size -A Male-to-Male Cable, connecting PC/Laptop to RedP? BUT don't you need to cross-over D+ and D-? {Analogous to RJ-45 Cross-over when you are going device-to-device. In the YouTube video By Elektor.tv "Red Pitaya: One Instrument to Replace Them All" the presenter (Speaker) said "...change  Adapter Settings..."

What? in a PC/Laptop? Don't you need a X-over? IDK (I Don't Know) of ANY PC/Laptop that allows an changing of wires. Do you know what the story is.?

Q6: Did you buy a Bare-Bones RedP or an RedP Development Kit?

Q7; Are You USA or Abroad? Did you buy local (to me: USA) or Foreign?

Q8: Do you think www.element14.com  might sell this RedP?

Thx

uscdadnyc (ny ny usa)

To Peter Oakes:

IDK I was blogging w/ a YouTube Star (you, Peter Oakes). AAR I am looking forward to your Youtube (follow-up) videos mentioned in your DEC 2015 "What's new". My previous Q5B is still Open. I know it was Not your video (it was elektor.com) but you are the Man! Thx.

I still have my old Textronix Oscilloscope Probes (X10, I remember), So Q9: I don't need the RedP Development Kit b/c the Kit comes w/ Probes? (which I already have). And the S/W load is analogous to getting RaspPi S/W, Correct?

Q10: I think I can run the RedP off my Android (Cyanogen Mod 11) rooted B&N Nook HD+ (via WiFi). But I guess it is time to spring for a new Laptop/Tablet. What types of options should I look for in a Laptop/Tablet? Options that are desirable when communicating/logging Data from the RedP?( a) SSD/HDD?, but the RedP has SATA connections(?)? (b) Optical Drive?, but Optical Drives have all but Vanished from Portables these Days. (c) USB ports ?(USB 3.0, most desirable) and lots of them.

BTW I recently bought a Student Edition of MatLab w/ simulink, and I believe there is C/C++ support (linkages) to/from RedP.? As there exists between MatLab and RaspPi.

Thx Again

-USCDADNYC

To Michael Kellett:

Pls elaborate on your comment below:

--------

Created 2 years ago by michaelkellett in Open Source Hardware

The issues in making  a decent oscilloscope go way beyond a micro. The Red Pitaya thing is an attempt at this but compared with a real scope it's just a joke. First you need the front end, input impedance 1M, variable (switcahble) gain from perhaps 100 to 0.01 in 1,2,5 steps with a flat frequency

______

Was this comment about the (current [timestamp 07FEB16]) Red Pitaya? Or was there a previous Incarnation? I appreciate that a low Impedance on Part of the measuring Instrument WILL affect the Readings (Think Heisenburg's Uncertainty Principle). But at a bandwidth of just 50MHz, are the implications that onerous? Sorry,

I did not do the Math yet.

BTW what about Bitscope? Same low Input Impedence?

-USCDADNYC (NY NY USA)

0 1 464

I was going to keep out of the RedP aspects of this thread but now that I've been asked ........

The RedP is an interesting attempt at a low cost instrument based on the Xilinx Zynq chip. It was massively over-hyped on it's launch with claims that it could replace instruments costing 10s of k$. The current web site is a bit more restrained  but still sadly lacking in detailed specs.

To take the inputs : a real scope has a wide bandwidth amplifier and either a switch or other means of selecting a wide range of gains so that the sensitivity can be set between a few mV per vertical division to perhaps 20V. As you pay more the ranges extend a bit and the precision and bandwidth improve. The other key feature they offer is some kind of DC offset control before the ADC - this is really useful. The RedP offers 20V or 1V, jumper selectable, and I'm not sure if its 1M impedance on both ranges. This will be so inconvenient that you will very quickly get totally fed up with it and either try to build an input amplifier/attenuator (which is very difficult) or give up and buy a real scope.

The RedP samples at  14 bits at 125MHz -  this is very slow - the cheapest Rigol samples 8 bits at 1GHz which is a much better compromise for a general purpose scope.

Try comparing the published data sheets of Pico, Rigol, Kesysight, Tektronix and LeCroy scopes with the RedP data - it's quite instructive - worry about the bits that don't get mentioned (and assume the worst).

The closest almost real scope to the RedP would be one of the Pico offerings (they do have proper switching ranges and input amps).

Remember that for useful work you need to be sampling at 10x the working frequency, so the RedP is good for up 12.5MHz.

I don't know anything in detail about the Bitscope - it's pretty cheap but I wouldn't want have to use one.

My advice is always to buy a real scope - if you can't afford  a new one then buy a second hand one.

I practice what I preach - my main scope cost more than my car - but I couldn't do my work without it.

MK

To MK,

Thx for your Candid Assessment on the RedP as opposed to Real Oscilloscope(s). Truth be told I am somewhat of Techie (having a BSEE from 1973) but I am looking for a "overview" Product. Not to get into the Nitty-Gritty of Designing/Testing, but some product that has the Basic Functions that show (maybe in a Limited way) Electronic Instrumentation. An Analog in Chemistry would be "Qualitative Analysis" Rather than "Quantitative Analysis". I am a USPTO Registered Patent Attorney, so my interest in what is available at any given Time/Place will (hopefully) constitute Prior Art. You have given me info about specs & capabilities that Must be considered (taken into account) when I evaluate the RedP to my (uncertain) Needs. Thx Again.

BTW I do have an actual CRT Oscilloscope. It is a Sony/Tektronix Dual Channel "Portable", circa early 1980's. It is under 30 years of Dust.

-USCDADNYC (NY NY USA)

Red Pitaya's main user interface is via the Ethernet port and is presented as a set of WEB pages, not X Windows or anything.

It does have SSH etc available to it and can have additional apps installed / compiled on it

Most of the Pitays analogue/signal processing functionality is handled by the FPGA, this is how it gets its great speed in processing of the inputs and outputs, the price of this is it runs very hot (Over 60deg C)

Right now, the Pitaya has the following main apps available (Some have multiple options and some you have to pay an additional fee for so it may not be as cheap as it appears

2 Channel Scope with the limitations michaelkellett has mentioned ( IE, 12Mhz ish true bandwidth assuming a 10X sample rate)

2 Channel Spectrum Analyzer

2 Channel Signal generator / Arbitary Waveform Generator upto the 125Mhz sample rate again but limited to less than a volt output (TBC)

LCR/reactance meter

Software defined Radio (New and I have not tested this yet)

you can run the ARB and Scope at the same time as there available in the same app, you cant run more than one app at a time on the main WEB pages due to locking of the IO devices like ADC etc I guess

The ADC and DACs are 14bits which is way better than most scopes these days (There all typically 8 bit), one benefit of this is that you get extra resolution out of a range compared to a reg digital 8 bit scope so this can in a limited fashon make up for no sub 1V range for instance as at 1V there is a 1/16384 V resolution... 61uV, this is way better than most scopes and is close to comparable with a 10 - 15mV range on a scope (15mV range would equate to a resolution of 61uV too) so perhaps to be fare we would round that up to a 20mV range. The point here is that any 8bit scope is not that accurate as it only resolves to 256 levels of a signal, scopes are primararly used to Look at the signal and get an idea of what it is doing

If your going to always or mostly be looking at logic level type signals or atleast limited to low voltages then 20V is not too bad but this is the base range, add a 10X probe and guess what, thats 200V. The input t the Pitaya is 1Mohm as mike sait which makes it ideal for adding a 10X probe if needed

Other features are DUAL SATA ports, a full set of GPIO so you could use it as a logic analyzer or control, Matlab / LabView capability, Scratch pogramming, and you could add your own custom apps too if needed, with our without leveraging the FPGA

Ill have more once I have done the review but thatshould help fo now

Oh, forgot to mention, Mine came from RS-Components for me to review so I did not have to buy it.  but you can get from Mouser, Direct from RedPitaya, from Eletor and a few other places. Oh and of course RS-Components. I did not find it on Newark though... sorry

Oh, forgot to mention, Mine came from RS-Components for me to review so I did not have to buy it.  but you can get from Mouser, Direct from RedPitaya, from Eletor and a few other places. Oh and of course RS-Components. I did not find it on Newark though... sorry

Kudos to Both PO & MK. You guys are the BEST. You guys cut down to the Chase w/o hyperbole. W/ the info gotten from you two, I can get a PhD in Oscilloscope (and wannabe's) Technology.

To PO:

PO wrote>>... [RedP has ]a full set of GPIO so you could use it as a logic analyzer or control...

ELY reply>> You just brought to Memory Lane again. In the 1970's, I had built a "Kit" Logic Analyzer. It was Only  8 bits.

USCDADNYC (NY NY USA)