Great news Hugh, thanks for posting first impressions.
#3 is of great interest to me as I tend to listen to music with significant bass content, though no-one likes to hear a bloated bottom end (at least, no one should like to hear it).
In light of the exciting work completed on this design (I have enjoyed reading the expert input) and the promising results I hope that I am able to get my hands on a pair of boards. Otherwise it might be time to test my hand at etching...
Cheers.
Tani.
#3 is of great interest to me as I tend to listen to music with significant bass content, though no-one likes to hear a bloated bottom end (at least, no one should like to hear it).
In light of the exciting work completed on this design (I have enjoyed reading the expert input) and the promising results I hope that I am able to get my hands on a pair of boards. Otherwise it might be time to test my hand at etching...
Cheers.
Tani.
Sorry Hugh
I didn't get any notification from this thread advisory for the delay in payment
I just sent the payment
can I ask for parts Sewell now? As I forgot to add that in my request
if yes-I can send the additional money
thanks for this PCB group buy
kannan
Kannan,
Thank you for your payment, received, I will post out on Monday. No problem at all with delay!
Hugh
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That's a very kind offer Hugh, though I'm actually in Dromana which is about 30 mins from Sandhurst so it might be too far our of your way... On the other hand a sunny day in Dromana is hardly a chore so if you fancy a beer... my shout.
Otherwise, I also have friends in Sandhurst so I could visit them and meet you somewhere... knowing those friends as I do, beer would probably be involved there too.
Cheers.
Tani.
There is an empty location directly below (south) of R11.
What fits there?
I just love the offset/bigger pads for the To92 devices. Easy to heat the pad before touching the device lead.
Is the * at the VR location an indication of the adjustment screw?
Has this been checked for clockwise rotation to "increase" the parameter being adjusted?
Is the a (anode) of the LEDs the -ve or +ve (short or long lead)? No square pad as polarity indicator.
7.5A seems to be overly high for PCB fuses.
For 8ohm speaker I would fit F2A or maybe F1.6A
For 6ohm speaker try F2.5A or F2A.
R15 appears to be located rather far from T5 gate.
Can we have an explanation of D1/2 A/B/C?
Is this the time to Launch a FetZilla Build Guide Thread?
What fits there?
I just love the offset/bigger pads for the To92 devices. Easy to heat the pad before touching the device lead.
Is the * at the VR location an indication of the adjustment screw?
Has this been checked for clockwise rotation to "increase" the parameter being adjusted?
Is the a (anode) of the LEDs the -ve or +ve (short or long lead)? No square pad as polarity indicator.
7.5A seems to be overly high for PCB fuses.
For 8ohm speaker I would fit F2A or maybe F1.6A
For 6ohm speaker try F2.5A or F2A.
R15 appears to be located rather far from T5 gate.
Can we have an explanation of D1/2 A/B/C?
Is this the time to Launch a FetZilla Build Guide Thread?
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Thoughts behind the FetZilla pcb design
Andrew,
You have an almost obsessive curiosity, someone must have traumatised you as a child when they said, 'Accept it, it's just the way it is'. In any event, your questions are reasonable.......
Design feature to help dissipate more heat from the TO92s both during assembly and operation. Inspiration came from the skull profile of the green monsters in 'Mars Attack' which are amongst my favorite scifi critters.
Yes, it's set up for the Bourns 3296W top adjust 25T trimpots. Yes, matches for P1 and P2, but not P3 unfortunately. It is difficult getting these right.
'a' marking on the LED holes is anode (positive), which is the longer lead. LEDs should be mounted high on the pcb, with at least 1cm lead length. This is to prevent early failure, as they are prone to swift failure if overheated during installation. The pads on LED2 have been drilled for 1mm pcb pins to attach flying leads to a remotely located LED. This gives the option for front panel indicator duties. If the LED fails, the offset will drop about three volts, which will give the speaker driver a nasty fright but will not destroy it.
The output devices are rated to 8A, and this gives plenty of headroom. Max required would be about 50% over max resistive current for reactive reasons (say around 6A), but your values are much too low and will have repercussions for sound quality since fuses are non-linear and thermal memory effects are considerable.
What, Andrew, one centimetre? Get off the grass, these FETs will tolerate three inches!! On a CRO this amp is solid as a rock, no oscillation at all.
These TO220AB BYQ28E (5A cont)/BYV32E (10A cont) packages contain TWO diodes with conjoined cathodes. You can thus make a full wave bridge with three packages, with the outer packages utilising just one diode in each. Compact, fast, inexpensive, and robust. I use this approach in many of my amps and it's utterly reliable and cost effective.
Sure. I normally do around 10k words and 35 photos, like my AKSA and Lifeforce series, but this takes about three months to complete, much of it consumed by error correction. Something simpler might be sufficient, but building these boards is pretty straightforward for someone reasonably experienced. My one criticism of the board is that the component designations for vertical mount resistors and diodes went astray in the gerber conversion, which is irritating; they are all slightly displaced to the right and down a little. This is a problem with early versions of Protel; gerber conversion is not flawless.
John Rowland, thank you for your payment! Boards on the way tomorrrow (Monday here).
Cheers,
Hugh
Andrew,
You have an almost obsessive curiosity, someone must have traumatised you as a child when they said, 'Accept it, it's just the way it is'. In any event, your questions are reasonable.......
Design feature to help dissipate more heat from the TO92s both during assembly and operation. Inspiration came from the skull profile of the green monsters in 'Mars Attack' which are amongst my favorite scifi critters.
Yes, it's set up for the Bourns 3296W top adjust 25T trimpots. Yes, matches for P1 and P2, but not P3 unfortunately. It is difficult getting these right.
'a' marking on the LED holes is anode (positive), which is the longer lead. LEDs should be mounted high on the pcb, with at least 1cm lead length. This is to prevent early failure, as they are prone to swift failure if overheated during installation. The pads on LED2 have been drilled for 1mm pcb pins to attach flying leads to a remotely located LED. This gives the option for front panel indicator duties. If the LED fails, the offset will drop about three volts, which will give the speaker driver a nasty fright but will not destroy it.
The output devices are rated to 8A, and this gives plenty of headroom. Max required would be about 50% over max resistive current for reactive reasons (say around 6A), but your values are much too low and will have repercussions for sound quality since fuses are non-linear and thermal memory effects are considerable.
What, Andrew, one centimetre? Get off the grass, these FETs will tolerate three inches!! On a CRO this amp is solid as a rock, no oscillation at all.
These TO220AB BYQ28E (5A cont)/BYV32E (10A cont) packages contain TWO diodes with conjoined cathodes. You can thus make a full wave bridge with three packages, with the outer packages utilising just one diode in each. Compact, fast, inexpensive, and robust. I use this approach in many of my amps and it's utterly reliable and cost effective.
Sure. I normally do around 10k words and 35 photos, like my AKSA and Lifeforce series, but this takes about three months to complete, much of it consumed by error correction. Something simpler might be sufficient, but building these boards is pretty straightforward for someone reasonably experienced. My one criticism of the board is that the component designations for vertical mount resistors and diodes went astray in the gerber conversion, which is irritating; they are all slightly displaced to the right and down a little. This is a problem with early versions of Protel; gerber conversion is not flawless.
John Rowland, thank you for your payment! Boards on the way tomorrrow (Monday here).
Cheers,
Hugh
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Hi Hugh,
Thought you'd like to know that another set of boards have arrived safely at their destination. I'd like to echo others here on the quality of design and manufacture. Many thanks for all your efforts.
I was just test-fitting some components, and noticed that you appear to have C7 and C8 voltage ratings swapped in the parts list. Both are 470uF, but I think C7 should be 16V and C8 should be 35V?
Cheers,
Ron
Thought you'd like to know that another set of boards have arrived safely at their destination. I'd like to echo others here on the quality of design and manufacture. Many thanks for all your efforts.
I was just test-fitting some components, and noticed that you appear to have C7 and C8 voltage ratings swapped in the parts list. Both are 470uF, but I think C7 should be 16V and C8 should be 35V?
Cheers,
Ron
I spent most of the afternoon un-soldering and re-soldering the rectifier diodes, at both ends of the PCB. The middle rectifier diode is oriented the same at both ends.
The half diodes are inserted different at the two ends. I lost count how many wrong combinations I tried and had to re-do..
The half diodes are inserted different at the two ends. I lost count how many wrong combinations I tried and had to re-do..
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