Upgraded My HP Touchpad in the Nick of Time

Back when HP was having its big Touchpad Firesale, my wife picked one up for me as a Christmas present. Loved it. A few years on, however, I find I am using it less and less, as it does not do the things I need. Simple things, like Citrix remote sessions, so that I can quickly login to work and help when an issue comes up. Even Netflix or Vudu would be great.

I had heard of people working on an Android build for the Touchpad, and after a few hours of poking around, I decided to try it out. I mostly worked with the information in this page: http://rootzwiki.com/topic/31548-rom-guide-how-to-install-android-23-43-on-the-hp-touchpad-the-easy-way/ Continue reading

Featured on dangerousprototypes.com

Imagine my surprise on Monday morning, when WordPress sent me an alert of significant activity on this site. Over 40 visitors within the last hour – that is very unusual. Usually it is much less than that per day. I took a look at the detailed statistics and all of the hits were coming in from dangerousprototypes.com. It appears someone had submitted my article describing a cheap power LED driver to their editorial team, and it got accepted! YAY! Continue reading

Manually disable vmreplica state (unable to extend disk)

Just ran into an issue with a VMware VM that was at one time replicated offsite using VMware’s replication tool. For some reason, when the service was decomissioned, (at least) one of our VMs was still marked as a replicated machine. When a VM is marked as active, then it will not be possible to extend the disk drive. In our case it appears that it was also in the middle of a replication, long since abandoned.

To fix, we found this article: StuffThatMightBeUseful

In the article, the author points out that the VM needs to be shut down. Probably better if the VM is down, but in our case we did not have this option and changed the setting on the running VM. Worked and did not crash. yet.

The steps are simple:

  1. Find the VM_ID (number in 1st column): vim-cmd vmsvc/getallvms |grep “name of your VM”
  2. Confirm current state: vim-cmd hbrsvc/vmreplica.getState VM_ID
  3. Fix: vim-cmd hbrsvc/vmreplica.disable VM_ID

Simple Constant Current Driver for a High Power LED

** Schematic diagram corrected and updated **

Update: New post highlighting a ATtiny85 based PWM LED Driver!

In my previous post, I slapped together a quick LED lighting solution for my workbench… but it is truly a hack. What I really want to do is make a simple constant current driver, so the power LEDs can be used in other projects. One of those projects is an LED swimming pool light. It needs to be running at maximum brightness and low cost.

Updated Schematic, correcting op-amp connections

After much digging and testing, I found a simple circuit using a power FET, an OP Amp and 0.5 ohm resistor.

Continue reading

Powerful LED Workbench Light on the Cheap

For a while I have been looking to instal LED lighting in my workshop,10wLED but every time I go to the DIY center, I look at the price tags and keep on walking. About a month ago, the Electronics Goldmine had a sale on 12V/10W/900 Lumen LEDs. $3 each! 900 lumens is equivalent to a 60 watt incandescent bulb. The datasheet I am using is here.

Once I received the LEDs, a quick test with my powersupply demonstrated them working VERY well, but running them from my bench supply would not do in the long term. A solution had to be found in my parts bin…

Continue reading

Pool Pump Controller – in Action!

Summer is finally here, and the hard work on the pool pump controller is starting to pay off. It looks like most of the bugs I ran into last year have been ironed out and it is working like a charm. Except when it doesn’t – but it quickly recovers.

In the video below, you can see the setup and a demonstration of its operation. Unfortunately, there is one more bug – when exiting high speed mode, the controller resets, but in 30 seconds it recovers and picks up where it left off. I think it is an EMP burst affecting the controller as it is in the same metal box as the relay.

A second gremlin sometimes affects the display on speed change, but the display refresh code eventually cleans that up.

For those needing a refresher, here is the initial writeup, and here is an update providing more info on the build, including code and schematic.