Thankyou for confirming Mr Albert!
I believe there is a 100 or 220uf cap following after that 47ohm resistor which is a bonus!
Unfortunately I have no 78L09s at the mo!
Also the Idq I had (3.11mA) Is not entirely accurate! It turns out that 3mA of that was just current consumed by the regulator itself!! Doh!!!
Looking on the bright side though I noticed as I approach 3V bias, the Idq starts to rise quite dramatically!!
I am really petrified to go any higher than 3V!!!
I think I will change the 78L05! Although voltage is present? It does not mean it is functioning as it should
Sinus Rig Repair
- sinus trouble
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Re: Sinus Rig Repair
I am as stupid as I look!
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Re: Sinus Rig Repair
Do you have a solid 5V at the output of the regulator? If you do, the regulator is OK.
"Why is my rig humming?"
"Because it doesn't know the words!"
"Because it doesn't know the words!"
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Re: Sinus Rig Repair
This is starting to make sense now. I think I might have mentioned earlier that I thought 3V was a bit high but it's been a good 10 years since I built with this device and the datasheet would appear to support what you're seeing. Don't forget it's the current you're interested in, not so much the gate voltage. Keep a close eye on the current as you adjust, and I would err on the low side, it's not worth overbiasing 30 quid's worth of FET for the sake of a few extra Watts which won't make much difference to your signal.sinus trouble wrote: ↑Tue Apr 18, 2017 10:34 pm Looking on the bright side though I noticed as I approach 3V bias, the Idq starts to rise quite dramatically!!
I am really petrified to go any higher than 3V!!!
- sinus trouble
- proppa neck!
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Re: Sinus Rig Repair
Spot on Mr Spanner!
I need to weigh up the pro's and con's in this situation? Do I push it and risk failure? Or leave as is?
I have put this rig through some harsh conditions and its still going strong!
Also it seems to be operating more in the class C region rather than B which can only be good for harmonic attenuation!
I need to weigh up the pro's and con's in this situation? Do I push it and risk failure? Or leave as is?
I have put this rig through some harsh conditions and its still going strong!
Also it seems to be operating more in the class C region rather than B which can only be good for harmonic attenuation!
I am as stupid as I look!
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- proppa neck!
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Re: Sinus Rig Repair
Not really. Class C has the device switching so there are some sharp edges that the harmonic filter has to deal with. Class B is usually cleaner!
"Why is my rig humming?"
"Because it doesn't know the words!"
"Because it doesn't know the words!"