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7th April 2008, 03:34 PM
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 Simple driver circuit doesn't work I'm designing a kind of light sequencer, in which a 4017 counter should light up incandescent bulbs (one at a time). It works, but the bulbs glow very faintly. I guess it has something to do with the driver circuit shown below.  The transistor is a small signal BC547B (max Vce=45V, max Ic=100mA, hfe=200). When the 4017 output is 12V, V_Bulb is only about 11V. It's a simple circuit, so it should work, I think... Any ideas? Would it help to have a resistance between the base and the 4017 output? /Christian | |
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7th April 2008, 04:25 PM
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hi, You picture posting is at fault.. can't see it.. 
__________________ Eric "Good enough is Perfect" PIC tutorials: Gramo's: www.digital-diy.net/ Bill's: www.blueroomelectronics.com/ | ||
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7th April 2008, 06:47 PM
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| Ok, I'll try again...  Hope this is visible /Christian | |
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7th April 2008, 06:52 PM
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1. Open a REPLY window, scroll down till you see a Manage Attachments button, left click. 2. Click Browse on the new window, this open your PC files, select your image file. 3. Click Upload, wait till its done [ref progress bar on window] 4. When its done close this window 5. Make sure your file type is accepatable Try again..
__________________ Eric "Good enough is Perfect" PIC tutorials: Gramo's: www.digital-diy.net/ Bill's: www.blueroomelectronics.com/ | ||
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8th April 2008, 12:03 AM
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| How much current does the bulb take? | |
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8th April 2008, 12:16 AM
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| 12V bulbs do exist but they are kinda specialized. If you're trying to light a 120VAC or 240VAC bulb you're going to be SOL. I didn't notice if you filled in your location.
__________________ We never have time to do it right; but we always have time to do it over. | |
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8th April 2008, 02:58 AM
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| Why doesn't he attach the schematic here so we can see it instead of trying to post it over there where it doesn't work?
__________________ Uncle $crooge | |
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11th April 2008, 11:25 PM
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| 12V is a pretty common voltage. 11V looks like what you'd expect from an emitter follower when you take into account the saturation losses. Your tiny transistor is wasting a huge amount of power and will burn up very quickly.
__________________ I also post at the following sites: http://www.stop-microsoft.org http://www.heated-debates.com Screen name: Aloone_Jonez | |
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12th April 2008, 02:42 AM
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__________________ The great thing about electronics is unlimited ways to do the job. The only limit is one\'s imagination. I generally think my way is best. Show me a different way. I have an open mind. | ||
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