6.3v indirectly heater valve PCB (possible group buy?)
- IslandPink
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#31
I love the smell of Veroboard in the ... evening .
"Once you find out ... the Circumstances ; then you can go out"
- Mike H
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#34
Wotchit with them strips, easy get short across if you're not careful - hint, bend component leads INLINE with the strips, not 'the normal intuitive way' at right-angles to.
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
#35
Quick update.
I have a working breadboard but the FET we decided to try isn't ideal, since we want to isolate the packages so we can use a single heatsink I have spent item looking for a suitable FET or bipolar in the same TO-200F plastic package.
This one looks promising http://www.st.com/internet/com/TECHNICA ... 001254.pdf
I'll get some in to try and report back.
Andrew
I have a working breadboard but the FET we decided to try isn't ideal, since we want to isolate the packages so we can use a single heatsink I have spent item looking for a suitable FET or bipolar in the same TO-200F plastic package.
This one looks promising http://www.st.com/internet/com/TECHNICA ... 001254.pdf
I'll get some in to try and report back.
Andrew
Analogue, the lost world that lies between 0 and 1.
#36
OK, here we go!
The TIP22 is installed, I used a green LED plus 1N4181 bias. The slight current difference is down to being on a slightly different part of of the TIP122 curves.
I'll do a layout now.
Andrew
The TIP22 is installed, I used a green LED plus 1N4181 bias. The slight current difference is down to being on a slightly different part of of the TIP122 curves.
I'll do a layout now.
Andrew
Analogue, the lost world that lies between 0 and 1.
#38
Here's the spectral output of the heaters at 900mA. Not much to see really, which is exactly what you want!
The worse is the 3rd harmonic at roughly -100db down. Also please bear in mind this is an unshielded breadboard and so will be picking up EMI. Full scale here on my magic box is 200mV on the lowest scale so 100db down is 200mv / 100000, so, basically, a fart in thunder!
cheers,
Andrew
The worse is the 3rd harmonic at roughly -100db down. Also please bear in mind this is an unshielded breadboard and so will be picking up EMI. Full scale here on my magic box is 200mV on the lowest scale so 100db down is 200mv / 100000, so, basically, a fart in thunder!
cheers,
Andrew
Analogue, the lost world that lies between 0 and 1.
- Paul Barker
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#39
Looks a lot cleaner than my signal generator!Andrew wrote:Here's the spectral output of the heaters at 900mA. Not much to see really, which is exactly what you want!
The worse is the 3rd harmonic at roughly -100db down. Also please bear in mind this is an unshielded breadboard and so will be picking up EMI. Full scale here on my magic box is 200mV on the lowest scale so 100db down is 200mv / 100000, so, basically, a fart in thunder!
cheers,
Andrew
#41
Hi Andrew,
Not sure what it will do to the price but it mat be worth making the tracks between the main input capacitor, bridge and input termianls as thick and short as possible as the capacitor charging pulses are significantly higher than the average current.
It may also be worth putting some holes under the heatsink fins to facilitate convection cooling.
I assume the input and output pad spacings are standard to allow termals to be fitted?
Best Regards,
James.
Not sure what it will do to the price but it mat be worth making the tracks between the main input capacitor, bridge and input termianls as thick and short as possible as the capacitor charging pulses are significantly higher than the average current.
It may also be worth putting some holes under the heatsink fins to facilitate convection cooling.
I assume the input and output pad spacings are standard to allow termals to be fitted?
Best Regards,
James.
#42
Yes, the pads are standard spacing so you can fit connectors. I checked against some spares I had from those e-bay mini24-96 DACs.
I have increased the track widths a bit on the ground line and on the input section.
I also fixed a bug I found, I picked the wrong part and so the pin out was wrong. As a result of changing the part I have now managed to get it all onto one side of the PCB
Here's the latest, suggestions are welcome. I'm seriously considered doing a one off using a light box and photo resist and chem etch process to make sure I have this right; especially if we're doing quite a few of these.
I was wondering what people expect in terms of a delivery date and if folks are willing to wait for me to verify that the artwork produces an OK PCB before I press the button on a run of 50 or so?
Andrew
I have increased the track widths a bit on the ground line and on the input section.
I also fixed a bug I found, I picked the wrong part and so the pin out was wrong. As a result of changing the part I have now managed to get it all onto one side of the PCB
Here's the latest, suggestions are welcome. I'm seriously considered doing a one off using a light box and photo resist and chem etch process to make sure I have this right; especially if we're doing quite a few of these.
I was wondering what people expect in terms of a delivery date and if folks are willing to wait for me to verify that the artwork produces an OK PCB before I press the button on a run of 50 or so?
Andrew
Analogue, the lost world that lies between 0 and 1.
- IslandPink
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#43
I'm happy for you to do a prototype first, Andrew - you'll probably pick up something you can improve, and it's best in the long run that it's got the bugs sorted .
What are the dimensions of this board currently ?
What are the dimensions of this board currently ?
"Once you find out ... the Circumstances ; then you can go out"