Entries Tagged 'Reviews' ↓

This is the MPJA 9615ps mini-bench power supply. The specs say that it will provide 0-30 volts and 0-3 amps. Mine actually goes up to 31.6 volts (displayed, measured to 31.3 volts on my lowest DMM) and has driven a short at 3.25 amps (verified with my DMM). As the previous sentence alludes to, the voltage display on my unit was 0.3 volts higher than my $50 Chinese DMM, and 0.1 volts higher than my $14 Chinese DMM. Given that my two DMMs don’t quite agree, I’m not willing to say anything other than the fact that I think it’s accurate to at least 0.3 volts. [The amp readings matched those on my DMM's.]

Pros:

• The unit is nice and small.
• The black on white backlit LCD is easy to read.
• The price…this sucker costs $50!

Cons:

• It doesn’t have a switch to turn off the output, so if you want to adjust it to a specific voltage before applying power, you have to disconnect it from your circuit, set the voltage, and then connect it to your circuit.
• The knobs set the maximum voltage/current, but the LCD does not display the set value unless you are at the limit. So it typically displays the voltage set point (if the load is voltage limited), and if you want to set the current to a specific amount (higher than is currently being drawn) you’d have to short the leads or connect it to a dummy load. If you want to set the current to what the load draws or limit the current draw, you can start it off at zero and move it up until it hits the value you want.
• The banana jacks to alligator clips the unit ships with are cheap. Notice those screw heads in the picture on the jacks? They are energized, so don’t touch!
• The fan on the back runs continuously. It is not a terribly loud fan, but it is audible. (Think a laptop GPU fan that kicks in when you run a video game….except it never turns off.) This doesn’t bother me, but I wouldn’t leave the PS running all day either.

All in all, I’m happy with my purchase. This supply does what it’s supposed to and makes it easy to power circuits and monitor their power consumption. It makes a great inexpensive hobbyist bench supply, or a 2nd supply for a professional who just needs to power something.

The Wreck of the River of Stars by Michael Flynn is a character driven space tragedy. The characters are excellent and the writing is superb. If you like happy endings, you shouldn’t be reading a tragedy, but if you like excellent writing you should read this book now.

The PICKit 1 is a combination programmer and development board for midrange PIC micro-controllers. In addition to being able to program FLASH pic devices, it also allows them to run and access 8 (charlieplexed) LED’s, a pushbutton switch, and a potentiometer. It’s a great little board for learning the basic of micrcontroller programing, but unfortunately it is not supported by Microchip’s new MPLAB X software (that is written in Java, and supports Linux/Mac in addition to Windows).

You CAN however use the PICKit 1 under linux. The piclab software is supposed to support it (I have not tested this). I use version 1.6 of the PicKit1 flash usb programmer for unix. Even the newest 1.6 version reports checksum errors after writing the hex file, but it does work correctly.

To make it work as an external program in MPLABX I had to select the “format HEX file for download” option under the Linker so that it would not fill all 2048 flash bytes when the program was smaller than that. I am able to manually run the usb_pickit command after building to flash the code, but it’s kind of annoying, as that program has a problem verifying the checksum and reports an error every time (which is interpreted as a build failure) plus, I have to run mplab X with root permissions to be able to access my USB port.

This is a photo of the radio transmitter inside of a Dakota Alert WMT-3000 wireless driveway alarm system. The wire coming through the hole drilled in the bottom of the case and soldered to the base of the antenna extends out to a 27″ wire whip antenna. Note the jumper circled in yellow. This jumper has a “high” and “low” setting. It is set to the “low” setting by the factory, and the “high” pin has been cut off. I found that the range was extended by soldering the “high” (cut off) pin to the center pin.

I have recently purchased a NetMedia iViewHD 2M power over Ethernet (POE) camera (retail price $105) for use with ZoneMinder.

This small camera must be hard-wired into a switch that provides power over Ethernet (which will cost another $80-100, but allows you to power up to 4 POE devices). I bought mine used, and plan on buying (up to three) more, but not at retail prices. If I find a similar POE camera with a better lens at the same price I would probably try it out, but at used prices the NetMedia iViewHD 2M is a good deal despite my image quality complaints below.
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So, if you purchase a few Jameco grab bags of potentiometers, what exactly do you get?

• 100 – 10 Ohms a good number, plus a few 20 ohms
• 500 – 50 ohms, a good number
• 101 – 100 ohms, a slightly smaller amount
• 201 – 200 ohms, a good number
• 501 – 500 ohms, a metric boatload (filled up 2 squares in my organizer)
• 102 – 1K ohm, a large number
• 202 – 2K ohm, a large number
• 502 – 5K ohm, two
• 103 – 10K ohm, three
• 203 – 20K ohm, eight
• 503 – 50K ohm, two
• 104 – 100K ohm, two
• 204 – 200K ohm, one
• 304 – 300K ohm, five screw pots, plus six larger slider pots
• 504 – 500K ohm, a large number
• 105 – 1 M Ohm, five
• 205 – 2 M Ohm, seven

Of course, if you wait a few months, Jameco’s overstock may be completely different and their grab bags may have completely different distribution of potentiometers.

We recently moved to a new house that is far from the central office, and apparently is served by some very old copper. AT&T’s computer system refused to sell us any DSL plans faster than 1.5 Mb/sec, as the lines wouldn’t support any faster speed.

I have tried using three different DSL modems at this house. In order of age and success:

1. Westell WireSpeed (2200) B90 DSL modem – This modem works at the full 1.5 Mb/sec speed, for a few hours. Then it gets slower and slower, until it averages 7KB/sec for downloads. (Uploads remaind at full 0.3 MB/sec speed). Power cycling the DSL modem fixes the issue and restores full speed for 12 hours or so.
2. Motorola Netopia DSL modem – This modem occasionally was able to get full download speeds, but typically would max out at 0.3 MB/sec (30 KB/sec) for the download speeds. (Uploads remained at a full 0.3 MB/sec.) Power cycling the modem did not improve things.
3. 2Wire 2701hg-B DSL modem with integrated wifi. This modem was able to maintain the full 1.5 MB/sec download speeds. Perhaps because it is the newest of the three modems, and has a better DSL chipset.

It was worth purchasing a new DSL modem for this house. (Although the Netopia and WireSpeed modems have both worked fine in other locations.)

This is a picture of a Rhode Gear Citadel ATB u-Lock that has been cut (and found next to where my bike used to be). I expect a large set of bolt cutters were used.

I have used a Motorola Backflip for a month, and am now trying out an HTC Aria. The Aria is a much smaller phone that lacks a keyboard, but has a newer version of the Android OS (2.1) and has a faster processor. For the rest of my comparisons, keep reading. Continue reading →

The Philips 900NC webcam is Linux compatible (Tested with: Ubuntu 8.10, 9.04 & 10.04). Under V4L2 it supports 640×480 at 15fps out of the box. (The webcam’s box claims speeds of up to 90fps, but that is only for smaller resolutions, custom windows drivers, etc. You may be able to get better speed with an optimized Linux driver, but out of the box performance is satisfactory.) It supports ZoneMinder, but only if you set up the exact correct Device Format (NTSC M) and Capture Palette (YUV420).
It has good low-light performance, although it will not work in complete darkness without additional IR illumination.