[Zigis]

Someone ask me to build portable amp with uncompromising high voltage power.
Here it is, in Hammond 1455J1202BK enclosure, 3x9V rechargeable battery inside
 
 

 
6.3mm phone jack, 3.5mm input on front, additional parallel RCA inputs on back panel, for use with home HiFi
system.
 
 
 

 
Wen I make photos, I had only last 5 screws at home, now amp is with all 4 screws on back panel  

 

[Zigis]

How can I make to see in thread photos, not links?

 

[ostewart]

nice one zigis, save the photos and then click on the photo symbol in text editor, then you can select the photos you want.
 
pricing?

 

[nikongod]

If you go into the "source" tab on the top left of the edditing field you can enter HTML directly.

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[Zigis]

Thanks randomkid and nikongod, now everything is visible!
 
To changing battery, back panel with 4 screws need to removing and 2 frontpanel's screws partly unscrewing, to slide top cower
 

 
Not very handy if you need to do it every few days. So we come to conclusion, rechargeable battery required. Next problem - for 3x9V=27V battery charging, at least 35V-40V PS required, hard to find and not cheap.
So, I made voltage multiplier with 555 chip. From standard 12V input schematic make about 40V at output, then 16mA CCS on LM317, red LED on back panel is in series with CCS and battery, it indicate real charging.
 
photo with my old cheap testing battery
 

 
Amp is build on breadboard, on side near battery you can see 555 and voltage multiplier, than LM317 CCS
 

 

[jcx]

9.6 V "9 V" rechargeable batteries are available

 

[ostewart]

You should try a LME49720 NA opamp, by far my favourite opamp

 

[Zigis]

jcx, yes  3x 9.6V=28.8V is little improvement, with my 40V charger it still can charge good.
 
randomkid, in the amp now is LM4562 with gain 2, really good sounding combination. I believe this chip is very close to LME49720.
 
I am drawing proper double sided PCB for this amp. At the moment just for fan, I would like for myself maybe 2 boards, to expensive to order.
However, if there are interest in PCBs from other people, let me know, we can make small group buy.
 
I can draw and post amp's schematic later, at the moment voltage multiplier is drawing on paper, amp's part (CMoy) somewhere in Internet, CCS somewhere else in Internet and whole amp schematic in my head

 

[Zigis]

Here is amp's schematic - voltage multiplier, CCS on LM317 and one channal.
 
 
 
     
 
Red LED is in series with battery and CCS charger, it light only if all 3 batterys are connected correct and 12V PS is connected, LED indicate real charging.
 
Battery (-) terminal is connected to amp through DC socket's normally closed contacts. Wen DC plug is connected for charging, contacts in socket disconnected and amp turned of.

 

[ralfderchef]

Yes, it is me...  I´m the first customer for this one...  First test are very nice, absolutely compareable to Zigisgs Desktop-cmoy... I have to listen to it for a couple of hours...  The idea to give it at a "no compromise"-Voltage was mine, the idea to make a build in chargins solution comes from Zigisg himself... Works great up to now...

Its still a prototype, but worth to make a platine layout due to actual standards...

This is not a marketing campagne, it is for making my high end listening portable...

Earbuds are UE Triple-Fi with custom earpieces, source is not MP3, only uncompressed music from all styles...
 
Ralf
 

 

[Boris-Aries]

Hello Zigis,
 
This is great. I actually had a similar idea, but different.
The link is here: http://www.head-fi.org/t/557103/new-power-supply-design-for-cmoy
The difference is, using Li-Ion.
I have not included the charging portion, of which is based on USB. I have already made an updated version, to what I have posted, that is for two Li-Ion, with Chargers. The preferred size of batteries I have, are the 18650 and the 14500 (AA).
 
There are 2 charging chips - for when using 2 Li-Ion, since I do NOT LIKE series charging, for personal reasons. It is built in "stages" (the voltage doubling) so you can either use as is, for a single Li-Ion or take one stage off for when used with 2 Li-Ion. Same design is also used for Ni-MH, just without the charging, due to that I could not get my head around NiCd / NiMH charging
 
Let me know if anyone is interested in the charging, part of the circuit
 
Also Zigis, I have some very old designs I had done for the cMoy, that made it very friendly for op-amp rolling. Let me know if you are interested, schematic only. I won't mind updating the design if you are interested.
 
Thanks for reading guys.

 

[DarkWinter]

I'd be interested in a pcb!

 

[Zigis]

 
Finally I am back to this project, PCB is designed, I am going to order probably next week.
 
In Rock Grotto forum wee discussed about this amp too, someone pointed me out to problem, which I didn't notice myself. Amp can work with power voltage down to 5V, in this situation rechargeable battery can discharge to level, where it is permanently destroyed. For 9V rechargeable battery min safe voltage is 7V.
 
So I include in amp battery voltage indicator, designed by aos:
http://www.head-fi.org/t/82115/low-battery-indicator-circuits/45
 
Here is new amp complete schematic:

 
And here is PCB, if someone see some error with a fresh eye, please let me know:
 
 
 
 
 
 

 

[Goobley]

I can't see any errors on that pcb after spending about 10mins comparing with the schematic. (difficult on an iPod though). I have to say I like the design.
The pcb is neat and tidy, do you trace by hand or autoroute?

Good work, I may well be getting one of these.
Chris.

 

[Zigis]

Thanks Chris, I make board with Sprint Layout, by hand. Spend few evenings to make it best, in my opinion of course.
 
If I get approval from at least 2 amps order (from people who have previously expressed an interest), I am going to order boards. Then will be spare boards available.
Zigis.