Having needed an adjustable power supply with a bit more current, I decided to buy this guy for about $140 off Ebay. I’ve played around with it a bit and I decided to review it because I’m sure there are a lot of people like me who buy cheap test equipment. You don’t pay much and you can’t expect much, but you can just hope it does the job.
I performed a few tests that you can see below:
So, if you looked at the values shown, you’ll see it works OK. Anyways, here are some pros and cons to this device.
Knobs and switched feel good
Nice high current for a unit like this
Nice grill effect over the LED’s make it look like a dot matrix LED
Standard size case
LOUD LOUD LOUD! Not quite vacuum cleaner loud but louder than anything else in my office.
Front power connectors are kind of flimsy and cheap
Displayed and measured values do not quite jive
Does not have a handle on the top, it’s nice to have a handle on test equipment
Otherwise, the unit works as expected and I’ll write the LED flicker off as a coincedence. It’s too bad that it’s so loud, they could’ve used a different fan or something, becomes a real distraction. If you need something like this that produces 30V at 10A, this may be good purchase.
A few weeks back I got my Mercury FPGA unit and what a nice little unit it is. The device plugs directly into a breadboard and could potentially be used as a drop-in for through hole PCB projects. When I got the unit I was impressed with it’s overall appearance, they sure packed this guy tight.
Having played with this a bit I can see the usefulness of this device. Here are some of the features.
A Xilinx XC3S200A-4VQG100C running with a 50Mhz oscillator
Complete with proper voltage regulation @ 1.2v and 3.3v
Some 5V tolerant IO pins
A USB port for direct programming and power from the USB port
A separate ADC with 8 channels linked to the FPGA
A couple of switches and a few indicator LED’s
You can program through the JTAG interface
You can use the Xilinx ISE design tool toÂ synthesizeÂ the project and you can use the Mercury software to upload it to the unit. Just based on the little bit I played with it, it seems to be a very useful unit. It’s great for learning (like I am to a degree) and is well designed and labeled on the PCB. There aren’t a lot of bad things I can say about this device except a couple of minor issues.
Issue one would be the sheer size of it. The unit fits on the bread board but with only one spot left on each side to connect things. This is a very minor issue and they did a good job making it as small as it is with as many pins and size of chips it does have, but having only one remaining pin could be an issue.
Issue two is its price. At $65 USD it’s a but more expensive than some other units out there. That said, they are unique in their pcb profile and the developers have to get paid for their time. My serial number was 147 so with such small batches, it’d be difficult to lower the price point. Hopefully it becomes wildly popular and the price can come down to a point where it can be considered a consumable of sorts.
Anyways, aside from my very minor complaints, this device is pretty cool. I can see all kinds of projects benefiting from a DIP style FPGA unit unlike the others which seem to have an arduino style PCB that makes it difficult to include in a project. I recommend that anyone who is going to learn FPGA’s give the Mercury a shot.
I decided to try out my new Hantek DS1060 and get some waveforms from the head of the EDM (Electrical Discharge Machine). The probe was hooked to the head of the machine and the ground was connected to the frame. I only took a few measurements but it may be interesting to some to see what the pulses look like when it’s cutting. This cut was burning at 75us on and 37us off.
You can see that the voltage doesn’t drop to zero, and there seems to be a dropoff after the ionization path has started to cut the material. These dropoffs after the spike seems to indicate that the path is ionized and current control has kicked in, providing 8 amps. Once the time is up, the current shuts off and then there is a ringing spike, perhaps due to inductance. From there the voltage doesn’t reach zero but probably sits at a continuity testing voltage for a little under the 37us. From what I can tell, 75us is started from when the ionization path is established, and 37us is the time it cuts off the current, event though there is still voltage (and maybe a bit of capacitiance).
The measurements seem to correlate to the settings a bit. The EDM itself is set for a 240V cutting voltage so the VMax of 181V is pretty close. I think those values are a quite flexible, I know that before it cuts at all, the voltage is at approximately 240VDC.
Anyways, I thought this would be interesting to post since some people are into EDM machines. I may take some waveforms from the wire EDM and two more different EDM’s. Here’s a final image of a zoomed in view of the peak.
Just wrote a little FreeBASIC program for calculating the length of the day and the difference from each. Just enter your latitude and it’ll output a text file for the length of the day and difference from the previous day.
Anyways, it’s not well programmed or anything but the function could be useful for somebody out there. Who knows