Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ.

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No. the lightbulb should be bypassed ASAP.

Posted by cheap-Jack (M) on April 23, 2007 at 11:34:47

In Reply to: using light bulbs when testing new DIY project posted by jarthel on April 22, 2007 at 19:03:43:

Hi.

A lightbulb will act as a series current limiter to the load (the amp) downstream of it. But once the amp warms up, the lightbulb got
to be bypassed ASAP to provide the full voltage supply needed for the load.

Why? A lightbulb tends to consume a MAJOR part of the supply voltage (being in series of the load downstream) when it is lit up due to its pretty high operation resitance.

I am still working on a better solution to half down the 220V AC mains voltage to an 110V rated audio equipment, without using a step-down transformer (a good one without impairing the sound will be hard to find let alone the cost), or a huge piece of series wire-wound resistor which runs hot hot.

I tried serieing lightbulbs of different wattage (hence dfferent operation resistances) but so far I've found the serie lightbulb
eats up to 70% of the mains voltage. No good for testing or running any audio components. Only for limiting starting currents, yes.

For my purpose pf halving down the AC mains voltage, a last resort may be a serie AC capactor upstream of the load. Again, where to get the cap of the right capacitive reactance is another hugh issue.

Let's see.

c-J

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