Analysis this schematic

[mohandes]

Hi to all.
this schematic is for ps g and i make it but i have not the values.
my problem in bd140,pin3 ne555 i have-10.35v but it should be 10v, drain of irf740 340v by multimeter but i have not voltage.
and i change ne5532 instead lf357n.
andin pin 6 lf357 should have -0.2v but i have 5.5to6.2v.
who can help me?please.

[mohandes]

No body help me
please

[Davor]

NE5532 is wrong, must be a single op amp with offset control towards positive rail. Use NE5534 instead.

[mohandes]

Hi davor
ok i change ne 5532 to lf357n.i think it is correct
thanks.but i have problem yet in drain of irf740 and pin6 lf357n ...

[Carl-NC]

The offset adjustment method for the 5534 probably won't work for the LF357.
Do you have an oscilloscope?

[mikebg]

VHF RINGING?

Mohandes, there's something that can be seen only with an very expensive oscilloscope, but you can hear it with FM radio. This is the VHF ringing of MOSFET, causing heating of IRF740 and interferences the input of preamp to operate normally.

Place the antenna of an FM radio near to damping resistor as illustrated. If you hear the TX repetition frequency on the radio, there is a VHF ringing. Connect a 22 or 33 ohm resistor direct in series to gate lead of MOSFET. The effect should disappear.

[mohandes]

The offset adjustment method for the 5534 probably won't work for the LF357.
Do you have an oscilloscope?

Hello Carl
i test by oscilloscope but i dont analysis the figre on the oscilloscope .i Drawing this figure and post for all,to help me.
in pin6 lf i have to have -0.2v but i have near 6v.and drain irf740 i have not 340 volt by multimeter so what is my wrong.
tomorrow i paste my Drawing

thanks

[mohandes]

Mohandes, there's something that can be seen only with an very expensive oscilloscope, but you can hear it with FM radio. This is the VHF ringing of MOSFET, causing heating of IRF740 and interferences the input of preamp to operate normally.

Place the antenna of an FM radio near to damping resistor as illustrated. If you hear the TX repetition frequency on the radio, there is a VHF ringing. Connect a 22 or 33 ohm resistor direct in series to gate lead of MOSFET. The effect should disappear.

Hello mike
I know that i shoude have in drain irf740 340 volt by multimeter and i have -0.7v and not hot irf740.i check my pcb and every think and i test by oscilloscope but have different result and dont know my problem, ithink my problem in bd140 or bc337 in path of gate irf740.
and what is the problem for lf357?can you help me ?
i drawing my result in oscilloscope(100MH) and put them.if this part is correct , i continue
thanks

[Carl-NC]

and drain irf740 i have not 340 volt by multimeter so what is my wrong.

If you are using a multimeter you won't see 340V even if everything is working correctly.

[mohandes]

Hi to all
now i send my pictures and need to your helps.please
have best time

[mohandes]

Hi my friends
I need to site for upload my pictures,i dont know what dont upload them,if you have a goo d site for upload ,Introduction to me please.
thanks

[mohandes]

ok finally i can upload
http://uplod.ir/fewfuo9yhb4i/help.zip.htm
please help and excuse for my bad write in the page.
thanks

[Carl-NC]

Sorry, can't read that site. You can upload pics directly to this forum, click Go Advanced, then use Manage Attachments.

[Geo]

If you are using a multimeter you won't see 340V even if everything is working correctly.

Carl, you are right. When i constructed it, with Oscilloscope reads 400....450 V p-p. So the value by multimeter will be much lower.

[Geo]

The offset adjustment method for the 5534 probably won't work for the LF357.
Do you have an oscilloscope?

Right..... offset at LF357 is at pins 1 and 5.