Pro Audio Design Forum

Brad Wood is using a http://www.nxp.com/documents/data_sheet/BF862.pdf in his new moving coil phono preamp.

At 0.8nV/rtHz pretty quiet part... Not as low input C as the 489 but a few pF is not that big of a deal.

Might make an interesting mic preamps... if they weren't already decent.

JR

Thanks for this Wayne. I have always enjoyed Cordell's work. That LSK489 looks like a sweet part, while I have to keep reminding myself that the world doesn't need yet another phono preamp. At 1.5nV/rtHz it is a little noisier than the 2SK117 (1nV/rtHz) I used in my last phono preamp (to end all pho...

Yup, it is pretty common practice to use clamp diodes across low noise transistors to prevent them from zener reverse breakdown (roughly 7V backwards across emitter-base junction).Transistors will lose beta and get noisy when allowed to zener. With an opamp there may also be issues with output state...

The recent storm that killed about 15-20 people from tornados dropped about 2-1/2" of rain in only a few hours so gave my new rain drain system a proper test. After the rain stopped my yard was damp, but no more 2-3 inches of standing water. The drain worked. :D :D I noticed that the cover for ...

Here is an old DIY helper I made... I soldered it to a battery clip so that would be heavy enough to keep it steady.

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We need low performance helper robots for all those jobs that don't require skill just another set of hands.

JR

Success I just ran a test with my garden hose,and the drain pulls down to the bottom of the 3" drain pipe, which is itself a few inches below yard level...Now I need to see if the outlet end stays clear over time... It is pretty low in my rain ditch. Lower than the bottom was before it was tren...

After seeing how much rise there is, I have abandoned any thought of regrading my entire lot, but bought a drain cache, and 50' of drain pipe that I am burying today. This should get a bunch of water out of my yard after it rains. JR [edit- when I thought I was near finished yesterday, a dropped a g...

It seems this has been well discussed here and elsewhere. For a generic answer I prefer door number 2, but to be accurate you need to draw resistors and little inductors in series with each power supply lead so you can better visualize what we are trying to manage. Something else I have surely menti...

I suspect the classic control approach is either a water level (float) or water present (contact) sensor, but I am thinking of just an automatic shut off. Something I can put in series with the pump line cord and detect the current draw difference from pulling water vs pulling air. It should only be...

Did you ever have a plan work out way better than you expected? I live on a low plot of land, bottom of a hill with front and back rain ditches. It is easy to see a lot of water flow through my area when it rains hard, and the crawl space under my house gets so much water in it that I have a sump pu...