555 timer turns on load via ground current loss help

285

03:02:20

I have a 555 timer at 141hz to turn off transistor every 7 seconds disconnecting ground from a load but the problem is there is current loss but I dont know how. Both 555 timer and load is powered by 5v 25a please can someone give me criticism lol I really want to get the device to powered but also reset ever 7 to 8 seconds. The circuit works except for the current being to low to drive device. 

published 11 years ago

MickeyD

11 years ago

I am using a transistor rated 700v 2a is only one I have available for load requirement.

cjdelphi

11 years ago

Are you using an NPN? 1k is not enough to saturate the transistor, lower the resistor to 200-300ohms... you may need a fet, I'm confused as to what you're trying to do..

Sine_eyed

11 years ago

Definitely the first thing to do is find yourself some scrap electronics to harvest components. Check with friends and family, ask around- almost everyone has something laying around they're not gonna use anymore. Old stereos, radios, VCR's, DVD players etc. have a shit-ton of parts to be had for you're current, and future projects. Also- check the website 555timers.com to learn the technical data of the chip. I don't think it wants a full 2Amps pushed through it! You might even find a helpful schematic while you're there..

MickeyD

11 years ago

Yes its npn I will try another resistor. I tried a mosfet, but found it to not work as good as bjt npn.

rbrtkurtz

11 years ago

"I have a 555 timer at 141hz...Both 555 timer and load is powered by 5v 25a..." I have no idea wtf you are trying to do. Is the 555 supposed to be the 141Hz source here? If that's the case, it will most likely be a square wave, not a sine wave. It doesn't matter so much what the load is powered by, what IS the load? Also 141Hz means 141 times per second. "Every 7 to 8 seconds," is .14Hz to .12Hz.

Mamish

11 years ago

This really sounds like a situation where an N-channel mosfet would work best. You can drive it with only a small resistance directly from the 555 and it only uses current when switching. But like kurtz said, it's not clear what you're trying to achieve.

diks_patel

11 years ago

i think maximum current output rating of NE555 is 200mA

MickeyD

11 years ago

I used bd681 it is working 100% now

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