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Old 4th August 2016, 07:35 PM   #91
vdi_nenna is offline vdi_nenna  United States
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Nice work Schube! You might have inspired me to fix my Sonograph mosfet amp that's been sitting for years.
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Old 4th August 2016, 07:46 PM   #92
kramskee is offline kramskee  South Africa
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Nice work Schubert, I must say I've never had much luck with those laterals, all the amps I've built used to break into oscillation at certain frequencies. Strangely I found the plastic version of the original Toshiba TO-3's to be more prone to this than their metal counterparts. As for these Hexfets they seem to be rock solid! ........... I thought it'd be fun to use a cheaper run of the mill hexfet like an IRF530 or similar obviously these 530 amps would be of smaller output power. So just sticking these in is no good, they have such low on resistance that they have to have source resistors! ......... so adding a 0.47 ohm resistor to the source of each transistor solves it nicely and makes for quite a nifty little 25-30 watt amp!

I've actually just finished designing PCB's for Nelson's Mosfet Citation with my own requirements in mind:

1. I wanted a separate plug-in driver PCB and a separate output PCB
2. I wanted as little external wiring with as little mounting hardware as possible
3. Fancy aluminium Extrusions are not always readily available here so I wanted to use a standard extrusion
4. After seeing Nelson's Complementary version I decided I needed to make my PCB's user selectable for either the Complementary or Quasi-Complementary version.
5. It also had to have a relatively small footprint.

So I managed to build an Amp module with a footprint of 38mm x 160mm with PCB mounted smoothing caps and it all fits neatly on a standard 50mm Aluminium square tube, the beauty about this is you can force cool it! and it just so happens that a stock standard 40mm PC fan press fits nice and snugly into the inside dimensions of the tube. In terms of mounting, 3 bolts hold the PCB to the heatsink. Output configuration is user selectable with a couple of jumpers and component changes.

I've built several prototypes they work well, I'll post some pics. I want to do a production run of 100 PCB's I'm wondering if anyone would be interested in buying any?
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Old 5th August 2016, 12:54 AM   #93
Nelson Pass is offline Nelson Pass  United States
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citation 12 mos fet
Most Excellent all round.

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Old 6th August 2016, 09:09 AM   #94
kramskee is offline kramskee  South Africa
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Default Citation 12 Reworked

Some Images as promised. Complete Amp with heatsink Length 180mm x Width 50mm. Pic no 4 & 5 show mounting arrangements, 3 M3 bolts hold it all together ( One under the fuse on the right ). output transistors act as the spacers too, these are thermally insulated from the PCB by a couple of small steel washers inserted between the PCB and the transistor. Note the bias transistor on the output PCB for thermal coupling. This fits into a 5mm hole in the heatsink.
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Last edited by kramskee; 6th August 2016 at 09:15 AM.
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Old 6th August 2016, 10:53 PM   #95
2 picoDumbs is offline 2 picoDumbs  Australia
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Quote:
Originally Posted by kramskee View Post
I've actually just finished designing PCB's for Nelson's Mosfet Citation with my own requirements in mind:

1. I wanted a separate plug-in driver PCB and a separate output PCB
2. I wanted as little external wiring with as little mounting hardware as possible
3. Fancy aluminium Extrusions are not always readily available here so I wanted to use a standard extrusion
4. After seeing Nelson's Complementary version I decided I needed to make my PCB's user selectable for either the Complementary or Quasi-Complementary version.
5. It also had to have a relatively small footprint.

So I managed to build an Amp module with a footprint of 38mm x 160mm with PCB mounted smoothing caps and it all fits neatly on a standard 50mm Aluminium square tube, the beauty about this is you can force cool it! and it just so happens that a stock standard 40mm PC fan press fits nice and snugly into the inside dimensions of the tube. In terms of mounting, 3 bolts hold the PCB to the heatsink. Output configuration is user selectable with a couple of jumpers and component changes.

I've built several prototypes they work well, I'll post some pics. I want to do a production run of 100 PCB's I'm wondering if anyone would be interested in buying any?

I'd be interested
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Old 7th August 2016, 08:00 AM   #96
kramskee is offline kramskee  South Africa
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2pico I sent you a message,

I see there are a couple of threads for the Mosfet Citation 12. Am I posting in the right place?
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Old 8th August 2016, 01:58 AM   #97
schubert is offline schubert  United States
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I looked at them all and this is the one with the most recent activity, so you're in the right place. Nice pics - if I didn't have two of these buggers already I'd be interested.
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Old 8th August 2016, 03:28 AM   #98
Junm is offline Junm  Philippines
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I had build two citation 12 Quasi version amps and my listeners like the sound. I want to try complementary and a ready made PCB is what I'm looking for..
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Old 9th August 2016, 11:05 AM   #99
kramskee is offline kramskee  South Africa
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Thanks Schubert, just found the facebook page too! .............

Junm boards are $6 for a single channel set

so if you're making stereo amps, $12 gets you 2 driver PCB's and 2 Output PCB's ......... PCB's will be FR4 1.6uM solder masked and component side silk screened for easy component placement. I decided on single sided PCB's since this makes it easier to repair and make any changes or modifications

Prices exclude shipping, I'm forced to use a courier service since our postal system here is unreliable at best
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Old 9th August 2016, 12:14 PM   #100
kannan_s is offline kannan_s  United States
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what would be the shipping costs to US? Approximate - interested in two stereo sets ( 4 Driver/ 4 output PCBS)
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