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quantrug
Joined: 05 Nov 2009
Posts: 6
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 05 Nov 2009 14:56 Mosfet Circuit check? |
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Please check the attached circuit and advice the necessary corrections.
thanks in advance
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hameeds01
Joined: 23 Aug 2005
Posts: 285
Helped: 11
Location: NUST Islamabad
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05 Nov 2009 15:32 Re: Mosfet Circuit check? |
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GATE pin of MOSFET is connected to Ground via optocoupler it is not getting any voltages, Optocoupler is used in a wrong way..
connect optocoupler PIN 4 to Gate & PIN 5 to +24v.
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quantrug
Joined: 05 Nov 2009
Posts: 6
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05 Nov 2009 20:50 Re: Mosfet Circuit check? |
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Will this do?
thanks
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quantrug
Joined: 05 Nov 2009
Posts: 6
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05 Nov 2009 21:39 Re: Mosfet Circuit check? |
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| slightly modified.
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Google
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05 Nov 2009 21:39 Ads |
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quantrug
Joined: 05 Nov 2009
Posts: 6
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05 Nov 2009 21:46 Mosfet Circuit check? |
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p.s.
R4 should read 15k!
Added after 2 minutes:
Please confirm if R4 should be 15 or 100k???
I have doubts now due different opinions.
thanks
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snafflekid
Joined: 09 May 2007
Posts: 118
Helped: 16
Location: USA
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06 Nov 2009 0:46 Re: Mosfet Circuit check? |
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| Is Q2 gate drive maximum 12V? That is how you are setting it. R4 will adjust the maximum gate drive voltage
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quantrug
Joined: 05 Nov 2009
Posts: 6
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06 Nov 2009 1:02 Re: Mosfet Circuit check? |
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| snafflekid wrote: |
| Is Q2 gate drive maximum 12V? That is how you are setting it. R4 will adjust the maximum gate drive voltage |
Thank you for the response, I guess the gate voltage at 12 will be all right. Below a report on the progress and the problems:
Hi,
So far on a proto board it's more or less...!
1-The voltage from the Arduino is about 5V but as soon as the Opto is plugged into the circuit, it drops to about 1.5v! Why?
2- However, the Opto is still working fine since on the other side of it utilizing a 12v for now, it shows about 12 with Opto inactive and when the Opto kicks in it drops to 12(source) - (1.5 from Arduino with Opto active) = 10.5!!! Why is the Arduino voltage being deducted from the 12v source?
3- The Mosfet is also functionin but sending just 1V to the solenoids!!!???
What am I doing wrong?
Each solenoid after Muliplexing will get to be on for just a couple of seconds every 15 minutes or so, but like every couple of seconds, a solenoid will get activated.
thanks
p.s.
the led doesn't function or maybe at .8v it just not showing? The solenoid does function with .8v but with no strength obviously.
p.s.s.
I am using a 10k and a 5k in series for the R4, that is not the problem or is it?
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hameeds01
Joined: 23 Aug 2005
Posts: 285
Helped: 11
Location: NUST Islamabad
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06 Nov 2009 4:53 Re: Mosfet Circuit check? |
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Replace R2(2.2k) by 820Ω
Replace R4 (10k) by 1K
Arduino has no relation with ur supply voltage 24V, the thing is that The Arduino is not that much capable to delivering more current to drive the opto coupler LED, u can use a current buffer b/w Arduino & optocoupler
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quantrug
Joined: 05 Nov 2009
Posts: 6
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09 Nov 2009 10:44 Mosfet Circuit check? |
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| Thanks Hameed, will do that.
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