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Rockbox mail archiveSubject: Re: JukeBox in the carRe: JukeBox in the car
From: Chris Muth <rockbox_at_muth.cc>
Date: Mon, 19 Jan 2004 15:33:06 -0600 On 1/19/04 at 8:21 AM [IDC]Dragon wrote: >Way too large, something like 100uF will do fine. The Archos has 220uF >internally (the older ones had less), but that's for driving headphone >impedance. >It's a good idea to have external caps if the voltage you're coupling to is >so high. The internal caps are only good for 4V or so. Use pulldowns on the >Archos side, to prevent that from being raised. > The 3300's were the only two identical caps in my parts box that were large enough. All the rest that I had two or more of were little 100,000pF (and such) ceramic caps. The 100Kohm's were on the Archos side of the caps. They are hooked between the (-)cap/JBR and ground. The (+) side of the cap is hooked directly to the main board in the radio where the tape deck board would normally have hooked up. >You don't need such high impedance. That unnecessary slows down the >leveling >of the caps when you switch it on. The Archos is driving with its headphone >output, which has maybe a few Ohms impedance. It's build to drive ~32...100 >Ohms, so you should be on the safe side with a 100 Ohm pulldown. If you use >higher ones, the voltage jumps up too much on power-up, the resistor won't >be >able to hold it down, you're overloading the internal caps which is harming >them. >Technically, you have a voltage divider between the inner resistance of >your >deck and the pulldown. > I noticed that if the 10v audio line is pulled to ground, it will effectively mute the audio that was going out to the speakers. When I had just the caps and no pulldown resistors, plugging the JBR in would mute the audio. The JBR side of the caps were at 10v just like the radio side. I wanted something big so that it would not cause the audio to get muted when I turn the radio on without even plugging the JBR in. I just had the 100Kohms sitting around from when I built an extra 10:1 attenuator for my scope (beyond the 10:1 that the probes were already) > >See? > Possibly. Received on 2004-01-19 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |