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74LS05 driving Relay

Many thanks to everyone who replied to my cries for assistance. Fred, I followed this diagram but I still only get 2.2V across the relay. Unfortunately, I'm so far out of my depth, I wouldn't have a clue as to what to try changing to increase the voltage. Any suggestions?

Thanks again...

(diagram reproduced for clarity)

5V | 1N914 +-------+---------------+--|----| o------+--|>|----+---| 2N2222A | |/ | |\ +---- | 74LS05 / e ON | 1K | | / | | \ | | | | GND----+-----------------+-----+
Reply to
Kyle Winters
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I read in sci.electronics.design that Kyle Winters wrote (in ) about '74LS05 driving Relay', on Sat, 29 Jan 2005:

Disconnect the 7405 output pin from the junction of the top 1 kohm and the diode. Now the transistor must be hard on if it's not damaged. What voltage do you get across the relay in that condition?

You haven't got the emitter and collector reversed, by any chance, have you?

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Regards, John Woodgate, OOO - Own Opinions Only. 
The good news is that nothing is compulsory.
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Reply to
John Woodgate

"Kyle Winters" schreef in bericht news:VzJKd.139752$ snipped-for-privacy@news-server.bigpond.net.au...

what

Seems impossible. Are you feeding the LS05 input with 60Hz noise or something? Connect the input to ground, and measure again. Also measure the other voltages, both sides of the diode and the power supply.

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Thanks, Frank.
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Reply to
Frank Bemelman

Reply to
Fred Bloggs

okay that sounds good

see

wouldnt

be

but that doesnt seem right. There is the work function where a charge builds up in the air so the voltage can conduct, since it never just "jumps" across an arc, it would be a fixed amount of energy/wattage but divides up with a high voltage, low current across the arc (or spark)

There is some chart I cant find now but shows the voltage relative to air pressure and gap width, the type of metal used has some effect, but it seems by guessing that a 3V supply making a spark/arc would have to be hitting around 100 v

Its not the same but a camera battery at 1.5 v or whatever is used to fuel the 1000's of volts needed for a flash

Reply to
Bradley1234

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