[Avro_Arrow]

You should set the current for 1C.
 
Here is the charger I built.
 

 
I just used parts I had laying around.
The heat sink is pretty big because I push it to extremes.

 

[tiagoncalves]

Today i'll start to build this project, i still don't have all the parts for the amp,so first it will be the trickle charger. if i use a 220 ohm resistor,instead of 240 ohm ,the pot will compensate for the voltage setting,right? i'll use two 4,7 ohm resistors in parallel to have a limit of 300mA,i found 9v battery with 300mAh.

 

[AmarokCZ]

Just like you said - 220Ohm is fine. Two 4R7 would be ~0.25A so it is fine too.

 

[tiagoncalves]

Finally, I ended the wood case, and started to assemble the electronics. The trickle charger is ready, and next week I start the amplifier, still waiting for some parts...
Here is the wood case:
 

 

 
And the trickle charger:
 

 
I choose two NiMH 8.4 V with 200 mAh, so I used a total resistance of 3.40 ohm (two parallel 6.80 ohm resistors). The other resistors and the zener diodes will turn off the led when the battery voltage is below 14 V, and a charge is needed. Should the turn off voltage be higher, maybe 15/16 V?
 
 
 

 

[Avro_Arrow]

The case looks really nice...good job!
 
Are you running the batteries in series?
 
If that it the case, then each 8.4 volt battery has 7 cells for a total if 14 cells.
14*1.5=21 volts.
You should set the no load voltage on the charger to 20 - 21 volts.
 
At 1 volt per cell, the battery is considered to be discharged, so 14
volts would be a good low voltage cut off.

 

[tiagoncalves]

Thanks, I had some help from a cousin, he works with wood and did a great job, and also I learned a lot about it. It was great.
That was just the settings I used, I set the potentiometer so get 21 V in the output. So, it must be set with no load? Great, I haven't the batteries yet, and I thought I would need to re-set the pot to achieve the 21 V with load. So, it's done, I can cross the trickle charger in the list of the jobs needed to be done.

 

[tiagoncalves]

I finally received all the parts, and yesterday I finished the A47 amp, using the next schematic, but with a 1,8 kohm resistor in R2 (instead of the 4,7 kohm):
 

 
Unfortunatly, I have a lot of distortion, and the DC offset is very high: 150 and 90 mV in each of the channels. What tests can I perform, to check the origin of this offset.
I check the voltage split, and is almost equal in both channels to ground.