Alright! Everyone is confirmed and invoices being typed up as soon as I post this. Final cost for the boards will be $7.00/board, which for the size run we had is pretty good IMHO.
I will be mailing out the boards in padded envelopes using USPS when possible and Global Priority Flat Envelopes for international shipments to keep shipping costs low. The shipping cost I put in the invoices was calculated by checking the USPS shipping, adding in the cost of an envelope, and adding $1.00 to offset the shipping from Advanced Circuits. (We only have 7 people in on the group buy, I will be picking up most of the $15 shipping cost, but I ordered many more boards than anyone, so no worries!)
Anyway, the TOTAL cost per board after everything is still less than the original $10 estimate (except for endzone), so I am happy!
Paypal is probably the easiest way for me to accept payment, so if anybody has an issue, please let me know (Except Tony, I know how you are paying, and that won't an issue). If not, as soon as I get enough confirmed payment I will place the order for the boards!
David
Group Buy Closed!!!!!
But, if you are still interested, let me know! I bought a few extra boards, but not many!
I will be mailing out the boards in padded envelopes using USPS when possible and Global Priority Flat Envelopes for international shipments to keep shipping costs low. The shipping cost I put in the invoices was calculated by checking the USPS shipping, adding in the cost of an envelope, and adding $1.00 to offset the shipping from Advanced Circuits. (We only have 7 people in on the group buy, I will be picking up most of the $15 shipping cost, but I ordered many more boards than anyone, so no worries!)
Anyway, the TOTAL cost per board after everything is still less than the original $10 estimate (except for endzone), so I am happy!
Paypal is probably the easiest way for me to accept payment, so if anybody has an issue, please let me know (Except Tony, I know how you are paying, and that won't an issue). If not, as soon as I get enough confirmed payment I will place the order for the boards!
David
Group Buy Closed!!!!!
But, if you are still interested, let me know! I bought a few extra boards, but not many!
Boards are in!
I put one together quickly to make sure everything fits, and it looks like the boards are perfect. I assembled this one using slightly oversized 1/2W resistors for everything, and they were a little cramped, but using 1/4W resistors (as the circuit is designed for) will be perfect. I test fit standard 1/2 and 1/4W resistors and both fit well.
I also try fit a bunch of different electrolytics, and all that I tried seem to do well.
I'll try and get the boards packed and shipped to everyone who has paid on Monday!
I put one together quickly to make sure everything fits, and it looks like the boards are perfect. I assembled this one using slightly oversized 1/2W resistors for everything, and they were a little cramped, but using 1/4W resistors (as the circuit is designed for) will be perfect. I test fit standard 1/2 and 1/4W resistors and both fit well.
I also try fit a bunch of different electrolytics, and all that I tried seem to do well.
I'll try and get the boards packed and shipped to everyone who has paid on Monday!
Attachments
No problem! I am just glad they turned out nicely. There is one silkscreen glitch (my faultdjkib said:
) but if I didn't really look for it I never would have noticed. Of course I caught the glitch 2 days after I sent the boards in! Still, nothing that will affect how the boards work. I'll see if I can scan in a better picture and post that sometime. David
After I get all of the parts ironed out that I like I would definitely consider it! So far I really like what I have seen from the prototypes, but I want to get a more robust output stage than the darlington configuration in the app sheet.
If you have specific parts in mind, I'll be happy to consider getting things together. Any suggestions?
PS I am using the Muse BP input caps bypassed with 1uf film caps if you are interested. I want to try a regulated PSU for the LM4702 stage to see how it does with an "unregulated" PSU for the output stage.
If you have specific parts in mind, I'll be happy to consider getting things together. Any suggestions?
PS I am using the Muse BP input caps bypassed with 1uf film caps if you are interested. I want to try a regulated PSU for the LM4702 stage to see how it does with an "unregulated" PSU for the output stage.
USA boards are in the mail!
I goofed and overestimated shipping. It turns out these will go by first class mail, making S&H $2.00 less than orignally calculated. I was going to roll that back into DIYAudio.com, but if anybody wants a refund, just let me know and I'll be happy to send it back.
International boards would be out too, but of course I forgot to fill out the customs forms, and the line was an hour long wait. I'll get those out tomorrow.
In the mean time, even though a regular waveform would be more diagnostic, the Mighty Mighty Bosstones are more fun to look at on a scope!
The (bad) picture below is just my iPod going into the LM4702 board with +/-35V unregulated rails, measuring the sink, source, and feedback wires tied together. From the tests I ran last night, the boards seem to work fine, though I did notice some very faint "hum" noise in the background when I cranked the sensitivity of the scope up. I couldn't see it until I really got to some pretty low levels, but it was there. When I grounded the mute pin, the noise did go away, so this is only there when the amp is on. I'm not sure what it was from, but none of the inputs were shielded, and the grounding was awful, so I am betting that once I get everything properly configured that will go away.
I goofed and overestimated shipping. It turns out these will go by first class mail, making S&H $2.00 less than orignally calculated. I was going to roll that back into DIYAudio.com, but if anybody wants a refund, just let me know and I'll be happy to send it back.
International boards would be out too, but of course I forgot to fill out the customs forms, and the line was an hour long wait. I'll get those out tomorrow.
In the mean time, even though a regular waveform would be more diagnostic, the Mighty Mighty Bosstones are more fun to look at on a scope!
The (bad) picture below is just my iPod going into the LM4702 board with +/-35V unregulated rails, measuring the sink, source, and feedback wires tied together. From the tests I ran last night, the boards seem to work fine, though I did notice some very faint "hum" noise in the background when I cranked the sensitivity of the scope up. I couldn't see it until I really got to some pretty low levels, but it was there. When I grounded the mute pin, the noise did go away, so this is only there when the amp is on. I'm not sure what it was from, but none of the inputs were shielded, and the grounding was awful, so I am betting that once I get everything properly configured that will go away.Attachments
BTW, I have noticed a couple of things while reading through the new National LM4702 Power Amplifier app sheet, and the good news is that almost all of the recommendations in that sheet follow what is in this board.
The exception, obviously, is taking out the input caps. This can be easily done by bypassing Cin with a jumper wire and feeding it directly to the first pin of Rin if you so desire. I am still playing with the input caps, but once I do this on one of my boards I will be sure to post some pictures if anybody wants.
If you have any questions about how to potentially modify these boards to match some of the aspects of the new amp note, I will be happy to answer them! Like I said when I offered these boards up, I tried to make them flexable, and based on some of the new ideas I got from reading this sheet, I will definitely configure the boards to take advantage of some of National's suggestions.
The exception, obviously, is taking out the input caps. This can be easily done by bypassing Cin with a jumper wire and feeding it directly to the first pin of Rin if you so desire. I am still playing with the input caps, but once I do this on one of my boards I will be sure to post some pictures if anybody wants.
If you have any questions about how to potentially modify these boards to match some of the aspects of the new amp note, I will be happy to answer them! Like I said when I offered these boards up, I tried to make them flexable, and based on some of the new ideas I got from reading this sheet, I will definitely configure the boards to take advantage of some of National's suggestions.
All orders are in the mail. Supposedly I can't use a scale since the post office consistently said my packages were lighter/cheper to mail than what I thought. Anway, there is a whopping $12 left over in the shipping fund, so the next time I send money to the forum I will tack on the extra.
It's not much, but I am sure every little bit helps.
Anway, packages should take about a week (possibly two for non-US shipments), so let me know when you get the boards so that we can identify problems if the occur.
Changing gears:
So far there are 3 people in for a parts buy (plus me, but I am always in!). What would everyone be interested in?
Off the top of my head, the last digikey order I made for parts for these boards had:
1/4W or 1/2W resistors (depends on what we want to go with. . .),
30pf mica caps
100nf bypass caps
220 uf panasonic FC caps
Ci/Cin caps (this warrants some discussion, I think)
1uf film Bypass caps
LM4702 chips
Comments about what values/brands you would like or want substituted?
I can also get TO-3 darlingtons that I have been using and some transistors for building simple output stages. I'm not sure who would be interested. . .
Let me know, and if we get enough interest I'll start making a formal list.
It's not much, but I am sure every little bit helps.
Anway, packages should take about a week (possibly two for non-US shipments), so let me know when you get the boards so that we can identify problems if the occur.
Changing gears:
So far there are 3 people in for a parts buy (plus me, but I am always in!). What would everyone be interested in?
Off the top of my head, the last digikey order I made for parts for these boards had:
1/4W or 1/2W resistors (depends on what we want to go with. . .),
30pf mica caps
100nf bypass caps
220 uf panasonic FC caps
Ci/Cin caps (this warrants some discussion, I think)
1uf film Bypass caps
LM4702 chips
Comments about what values/brands you would like or want substituted?
I can also get TO-3 darlingtons that I have been using and some transistors for building simple output stages. I'm not sure who would be interested. . .
Let me know, and if we get enough interest I'll start making a formal list.
hey Craig,
Glad they got there OK. As for the BOM, I haven't put one together since I figured people would pick thier own resistor/cap combinations. I'll be happy to put one together quickly based on what I am using presently, but it will probably be some time tomorrow. In the mean time, I'll post my spreadsheet for calculating component values. Feel free to ask questions if the sheet isn't self explanatory.
David
Glad they got there OK. As for the BOM, I haven't put one together since I figured people would pick thier own resistor/cap combinations. I'll be happy to put one together quickly based on what I am using presently, but it will probably be some time tomorrow. In the mean time, I'll post my spreadsheet for calculating component values. Feel free to ask questions if the sheet isn't self explanatory.
David
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