On 14 June 2013 05:48, Perry Sandeen <[email protected]> wrote: > There are two long standing truths about > electronic equipment. One you can’t have > too much filter capacitance. Two, you > can’t cool too much. (Please spare me > the liquid nitrogen or submarine battery > comments.) > > Regards, > > Perrier
Well, I have to disagree with both comments. More filter capacitance in a standard linear power supply means the diodes take more current for a longer period of time. For any given diode, that puts more strain on it. At very high levels of capacitance, the amount of stored energy is huge, and can be dangerous. In the event of a fault, higher stored energy has the potential to do more damage than lower stored energy. Once you have sufficient capacitance, which includes calculating the effects of reduced supply voltage, minimum capacitance of device with tolerances, and some safety factor, I don't see what more capacitance does other than increase costs, weight, and the potential for more damage in the event of a fault. Whilst it is well known that increasing temperature gives rise to shorter component lifetimes, more cooling also requires more noise, and so a compromise has to be met. I have here an Air Control Industries VBL9 blower, which I want to sell in fact. That will move about 1000 cfm at 6" of water pressure. It happens to take 2.8 kW from the mains, the startup current is too large to not blow a normal mains fuse in a plug here in the UK, and the noise is enough to get neighbours wondering what the hell it is, despite I live in a detached house, some 50 m from the nearest property. So while a HP 5370B needs far more cooling than provided, I think the VBL9 would certainly provide too much cooling air. Engineering is always a compromise. HP usually got that balance about right, although in some instances, like the 5370B, that is not true. I know mine got pretty damm hot, and I'm quite near sea level. I would imagine for someone at a high altitude, it would be even worst. I have to agree with you about the serviceability of older HP equipment though. It is much more serviceable than modern equipment. However, you would have to go back a long way before finding equipment which one could guarantee one could keep going, as most things I'd contemplate buying will have a ASIC and/or some other specialist component which if it failed would be impossible to get except by taking one from a similar piece of equipment. Dave _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
