Recent Posts

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Machine Shop / Re: API knobs
« Last post by rackmonkey on Today at 12:04:33 AM »
Do you have access to a lathe, even a small, cheap one? If so, you can get the drill bit and the knob perfectly aligned/centered every time with a drill chuck inserted into the dead center side.

Another trick if you don’t have access to a lathe: tightly clamp two 3/4 inch thick boards across a drill press table one on top of the other. Drill a hole the same outer diameter as the knob a little less than the height of the knob in depth into the wood (for an API knob, measure across the wing edges for the diameter. If you don’t own calipers, it’s easiest to compare the non-fluted side of the drill bits with the knob against the end of the bit. Better to go a hair smaller in diameter than a hair bigger, as long as you can still get the knob into the hole you drill without much force. A forstner bit will work if you don’t have a big enough twist bit). Making sure not to move the boards, push the knob into the hole. It should fit snugly but not so tightly that you have trouble pulling the knob back out.

Drive a screw down into the hole between two of the wings to prevent the knob from spinning when you drill into it (you might want to wrap the screw with a few layers of duct tape to keep from marring the knob as you drill it out. Two screws between different sets of wings is even better). Now change over to the 1/4 inch bit and drill out the mounting hole.

Remove the knob (you may need to use long nose pliers with a layer of duct tape around the ends) and repeat for the rest of the knobs.
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The Lab / Re: GE BA-5-A capacitor replacement help
« Last post by rackmonkey on Today at 12:01:38 AM »
Do you have pictures of the whole unit you’d mind sharing?
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Drawing Board / Re: What's up with OEP?
« Last post by rackmonkey on January 21, 2021, 11:58:19 PM »
The Carnhillification of all the UK transformer manufacturers rolls on.

Are there any left that Carnhill hasn’t bought up?
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Microphones / Re: Official C12 Clone - Build and Support Thread
« Last post by doggy6812 on January 21, 2021, 11:32:33 PM »
Hey guys. I have built two of these and have problems with the pattern switch. It seems the mic wants to both sides of the capsule on. I can turn the switch to Cardiff and the rear capsule will go off for just a second and then comes back on. It also does the same thing In Omni. They both do this
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Microphones / Re: Official C12 Clone - Build and Support Thread
« Last post by rmburrow on January 21, 2021, 11:12:12 PM »
33 megohms within 10 percent of 30 megohms, should work...time constant of capsule and polarizing resistor(s) would increase very slightly..
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Filters/Equalizers / Re: EQP1A Standard Test Procedure
« Last post by dbonin on January 21, 2021, 10:04:25 PM »
Thanks Ian, Doug.
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Brewery / Re: Raspberry Pi does it again
« Last post by Gold on January 21, 2021, 09:47:34 PM »
We also hired someone from Hopkins last year who stuck one in a rocket hooked up to a radio transmitting flight data as a cheap black box.

From APL? My uncle spent his career there.
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Microphones / Re: Official C12 Clone - Build and Support Thread
« Last post by Haberdasher on January 21, 2021, 09:40:36 PM »
I somehow neglected to order 30M resistors (I used 100M for R15, 16).  Looks like mouser is out of stock.  I do have metal film 33M here for R11 Vishay VR37000003305JA100.  Is that going to be ok?

Thanks
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Brewery / Re: Raspberry Pi does it again
« Last post by midwayfair on January 21, 2021, 08:59:58 PM »
Nice price. They've come down quite a bit. A few of the people in my OS class used them for their term projects, one of which controlled a drone. We also hired someone from Hopkins last year who stuck one in a rocket hooked up to a radio transmitting flight data as a cheap black box.

When I was a kid, we actually did learn some programming in elementary school, but it went away a few years later (the closest thing when I was in high school was a basic computer literacy course -- typing, office suite, etc.), and when I was working as a sub after my first degree, it wasn't being taught at any grade even in the magnet public schools. It's starting to come back as the school system discovers that some familiarity it is a basic modern life skill. Hell, the BASIC my dad taught me when I was 6 paid off when I was working as a science editor in my 20s. I can't fathom why it didn't just stay part of the curriculum.
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