On Sat, Feb 18, 2012 at 08:28:03AM -0500, gene heskett wrote: > Something I didn't consider in my first generation design since I was still > learning myself, which although it had an output impedance at the TLO84 pin > of under an ohm, then used 300 ohm per leg build outs. The next generation > card, the main design change was to change that 300 ohm to 30 ohms. This > then worked much better out in the newsroom, but was even more susceptible > to the emp spikes the longer runs picked up. Since the card had to fit the > cage, it never did grow the schotkey power diodes to the supply rails that > would have absorbed those spikes, no room left on the the card for diodes > that at the time (1984-85) were about 1/2" long & 1/4" in diameter. It > would have taken 12 of them to protect the inputs as well as the outputs. > These cards all had their own rail regulators (78-7915's) for +-15 volts as > the cage supply was about 22 volts +-, filtered some but not regulated, > good for about 10 amps a rail. 22 cards with 44 pin edge connectors in one > 3 space high rack, it did have noticeable but tolerable heat output. The > only place with enough farads available to dump the emp was the main rails, > and a quick test of that idea using a bench supply showed that wasn't a > cure as the output stage of the TLO84 was still destroyed when the output > was pulled above or below the cards internal +-15 volts by about 2 volts, > long before the schotkeys to the +-22 volt rail would turn on.
Should I feel sorry for all those poor TL084s that died while being forced to work well above their physical limits, abused and expendible like Egyptian slaves building the pyramids ? :-):-) > So now the problem is levels, digital doesn't come > with a knob. The std, if there even is one, is ignored, which explains the > commercials that are 20db louder than the program, nobody cares and we > catch hell from the listeners. You mean there's *no* volume control between whatever is used to play commercials and the transmitter feed ? No continuity A/V mixer at all ? Ciao, -- FA Vor uns liegt ein weites Tal, die Sonne scheint - ein Glitzerstrahl. _______________________________________________ Linux-audio-dev mailing list [email protected] http://lists.linuxaudio.org/listinfo/linux-audio-dev
