Dead Woofer in Opera Active PA Speaker

The other day I got my two Opera Live 210 active PA speakers out and I noticed that in one of them only the tweeter was working. Oh no! So I decided to take it apart since it is way too old to be eligible for warranty. I was really surprised how well designed they are! Everything is neat and clean and almost as if they are made to be taken apart. What I found though was’nt that cool: I measured resistance of the speaker coil in the woofer with my multimeter and got an incredibly low .6Ω. Well I guess that means that it is practically shortened, probably in an overload situation. That’s very strange since these speakers are active and have a built-in overload-protection-circuit. I guess it didn’t work so well. ;-( To see if the part of the active amplifier that drives this speaker still works I hooked up my multimeter to its outputs without the woofer being connected. Turning the volume up or down didn’t change the displayed 0V. My guess is that this means that the short in the woofer also killed the amp in the process. That’s really too bad, because I really liked these speakers. They are no longer manufactured.

One funny thing I also found is that some screws had come loose over the years. They are used to mount the OpAmps to a cooling brick. One of those three screws had vanished so I looked around inside the case and I found it: it was clinging to the speaker’s magnet!

Listen to the awful sound of only a tweeter. I recorded the speaker before taking it apart:

Vandal Spur Gear Protection

Because the Vandal’s spur gear always drags in the dirt when racing this awesome car it is subject to significant wear. To protect it a little bit from the sand I cut out a tiny piece of plastic that I glued to the bottom of the chassis frame with some CA and then covered it with duct tape. I hope it lasts longer this way.

plastic glued on w/CA
plastic glued on w/CA
added duct tape
added duct tape

Vandal: loose screws

After my first ride with the Vandal yesterday, the front wheels had lost power. I figured something must gone wrong with the front diff. So today I opened up the Vandal and discovered, the screw that holds the drive shaft to the gear box simply had come loose.

Vandal images for Taranis

I created two pics of the Quanum Vandal for use as a model symbol in the FrSky Taranis Transmitter. Feel free to download and use them yourself!

vandal1 vandal2

My Taranis

I recently sold all end every piece of Spektrum equipment I had and converted all my models to FrSky technology. I really think it’s the best there is! Taranis Homepage

But I still want a transmitter that works for my Blade mCP X, Nano CP X and 130 X helis, so I decided to build my own transmitter module to use in the Taranis’ TX module slot. Out of my old DX4e I extracted the HF module and soldered it into an empty Spektrum case. Now I have true DSMX in my Taranis. To do this I followed this comprehensive article by John Prikkel.

 

HD-P2 powered with LiPo

One of the big downsides of the Tascam HD-P2 audio field recorder ist that it runs on 8 AA batteries. They don’t even last a day and it’s not very fast to change them all out in the middle of a production day.

So I decided to make an adapter to connect my 3S 3000mAh LiPos to it. I simply cut up the cord of its AC wall adapter and soldered two XT60 connectors to the open ends. This way, the AC adapter can still be used, but the new short adapter cord is perfect to connect to the LiPos. To be able to detect low voltage in the LiPo cells I simply hooked up a small LiPo alarm to its balance plug.

This setup proved to be very useful and the 3000mAh battery lasts at least one and a half days!

Tiny nano Quad on the Oscilloscope

Just out of fun I hooked my tiny little Revell Mini Quad Copter Nano Quad up to the oscilloscope to see at what voltage these little motors are operated. The are obviously driven by a pulse modulated signal of 3.2V peak-to-peak (or whatever the battery can deliver). The pictures show throttle of 0, half and full:

first dynacho pics