solderdude
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Post by solderdude on Apr 15, 2020 21:32:46 GMT
Batteries are probably dead.
Just unplug one of the batteries (they are in series) and use the amp directly from the powersupply.
Should work fine with high imp. headphones this way.
Then take out the batteries and measure the DC voltage.
All the Vapex batteries I had are all gone now.
I reckon none of them reached the minimum 500 charges.
Well.. mine is now 5 years old and the few mobile phones we had over the years also needed new batteries after about 3 years (if the phones managed to live that long)
Currently using some 9V batteries from Conrad of about the same capacity.
They are in there for a year now and are almost daily under charge and used quite a few times a week.
Charging circuit will be fine.
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Crispy
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Post by Crispy on Apr 16, 2020 18:02:35 GMT
Batteries are probably dead. Just unplug one of the batteries (they are in series) and use the amp directly from the powersupply. Should work fine with high imp. headphones this way. Then take out the batteries and measure the DC voltage. All the Vapex batteries I had are all gone now. I reckon none of them reached the minimum 500 charges. Well.. mine is now 5 years old and the few mobile phones we had over the years also needed new batteries after about 3 years (if the phones managed to live that long) Currently using some 9V batteries from Conrad of about the same capacity. They are in there for a year now and are almost daily under charge and used quite a few times a week. Charging circuit will be fine. Thanks Frans. I took the batteries out - what a job, the double sided tape holding them in was like cement. Battery One tested at 9.16V so OK? Battery two tested at 7.98 so OK but in need of a charge? I then plugged the 9.16v battery in and tried to charge it - yes no problem I then tried the 7.98v battery and no it would not charge. I had a thought that I might of got the wires mixed up as they all look the same and twisted together, so I untwisted them all and tried again. wires from the left side of the board would not charge either battery. wires from the right side of the board would not charge either battery. I then took the + from the left side of the board and the - from the right side of the board and both batteries would charge from that? I took the - from the left side of the board and the + from the right side of the board and it would not charge either battery. Mistery to me Frans - so I have left the case open with the 7.98 battery charging up and i will test it again tomoro. Any Idea what the problem could be? |
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Crispy
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Post by Crispy on Apr 17, 2020 17:53:38 GMT
Update:
The battery I left charging overnight read 10.45Vdc this morning - so the batteries seem OK to me.
I thought I would do a bit of investigating and put the multimeter on the charging wires.
Left side read 0.01 Right Side read 0.01
So I thought the battery management mod may be the problem.
It looked like the capacitor had been flattened down and I thought the + leg was touching R13 and possibly IC3, so I raised it up and measured again. Same result.
I re-looked through the Kameleon PDF manual and noticed on page 10 that it says the jumper for ALK/NiMH should be set in the magenta position, mine was in the ALK position? This is confusing beacuse the jumper on the board is the wrong way around?
I have just noticed in new battery management PDF that it says the ALK/NiMH selection jumper has the text in the wrong position on the PCB.
It also says R10 must be replaced with a 150K resistor - mine has 100K, it also says D4 & D5 should be replaced with BAT54C. I cannot remember what mine are but can only just see some markings on the top that say WW1 - which I think are BAT54C?
I don't know if any of this makes any sense to you Frans - I tried to keep it simple  NOT
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solderdude
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Post by solderdude on Apr 17, 2020 18:43:29 GMT
It looks like a dead battery.
Does the amp work normally without batteries connected and connected to a charger ?
The 8V and later 10.45V is suspect and the battery may not hold a charge.
You can also check the battery voltages when operating.
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Crispy
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Post by Crispy on Apr 18, 2020 15:03:48 GMT
It looks like a dead battery. Does the amp work normally without batteries connected and connected to a charger ? The 8V and later 10.45V is suspect and the battery may not hold a charge. You can also check the battery voltages when operating. Thanks Frans, it does look like dead batteries.
The amp works fine without batteries and connected to a charger.
I watched a you tube video about testing 9V batteries explaining why open circuit voltage readings are meaningless.
So I used my expensive multimeter and measured both batteries - one read 8.44 & the other 8.82.
The tutorial said anything over 8V should be OK? - but if you put a 5W resistor across while measuring the voltage should hardly drop.
When measuring both batteries with a 5W resistor in place they both dropped to 0V.
So dead batteries confirmed.
Time for new ones
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Crispy
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Post by Crispy on Apr 19, 2020 19:22:22 GMT
Currently using some 9V batteries from Conrad of about the same capacity. They are in there for a year now and are almost daily under charge and used quite a few times a week. I had a look at Conrad's site for some 9V batteries and noticed they do Li-ion batteries as well.
This is a stupid question which I probably know the answer to before asking, can the Kameleon use and charge Li-ion batteries?
Are these the ones you are using at the moment? |
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Post by solderdude on Apr 19, 2020 21:30:55 GMT
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Crispy
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Post by Crispy on Apr 20, 2020 19:56:12 GMT
Thanks Frans.
I had a look around and did a little research and EBL batteries seem to get a good review.
So I found these on Ebay @ £16.10 for 4 - which works out @ just over £4 each, so they are cheap enough.
They reckon they are slow discharge, can be charged up to 1200 times and have overcharge and overdischarge protection, temperature, short ciruit, output overvoltage and output overcurrent protection. Too good to be true EH?
I think I will use the two spare batteries for my mulitmeters.
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Post by solderdude on Apr 20, 2020 21:55:04 GMT
£4 is not expensive for 'ordinary' LSD NiMH batteries. The "can be charged up to 1200 times and have overcharge and overdischarge protection, temperature, short ciruit, output overvoltage and output overcurrent protection.' might be true for the Lithium batteries as they have battery management inside. The NiMH version is just a simple battery. www.eblmall.com/product/2-pack-rechargeable-9v-batteries-low-self-discharge-long-life/I reckon they will do the job well for the coming years. |
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Crispy
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Post by Crispy on Apr 21, 2020 17:35:34 GMT
The "can be charged up to 1200 times and have overcharge and overdischarge protection, temperature, short ciruit, output overvoltage and output overcurrent protection.' might be true for the Lithium batteries as they have battery management inside. The NiMH version is just a simple battery. I reckon they will do the job well for the coming years. Yeh I thought they were too good to be true
Their advertsing is slightly misleading - but for £4 I don't care, and like you say they will do the job for quite a few years?
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Post by justin on May 24, 2020 9:44:53 GMT
Hello Frans.
After it being sat under my desk for nearly 2 years, I have finally just completed my desktop Kameleon build. Thank you for this design, it’s a good challenging build and so far sounds excellent.
I need some advice please.
My potentiometer has channel imbalance just above zero volume but normal listening levels for my Focal Spirit Professional headphones is only just above that. Zero volume starts at 7 o’clock on the pot, channel imbalance is there until 8 and too loud is 9. Using my HE-400i I can still only get to 10 o’clock.
I am using the standard 10k Alps pot from the BOM, 2x gain filter and OPA1612 op amp. The DAC’s I have give a 2V line out.
Before I change things what are my best options? Try to replace the pot with a better one, increase to 50K pot, 1x gain filter, something else?
Also when I build some filters for my headphones I would like to ensure that decent listening levels are nearer to the 12 o’clock position on the pot. What gain is applied to the filters and is it easily modified?
Thanks,
Justin
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solderdude
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Post by solderdude on May 24, 2020 10:09:02 GMT
Hi Justin,
There are several ways to solve this.
1: lower the volume digitally from the source.
2: change the values of R102 and R202 to smaller values. Say 10k or so. Changing the potmeter value won't change the volume control much.
Alas other ways of lowering gain are not possible and will affect the filter properties. The gain on the filters is fixed in its design and based on efficiency of the headphones.
The original design (gain) was based on the kameleon being portabble and being fed with a phone or small DAP. These usually have a very low output voltage level so more gain was needed.
For this reason R102 and R202 were implemented so you can have some control over the overall gain.
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Post by justin on May 24, 2020 10:26:52 GMT
OK thanks Frans, I shall look at replacing R102 & R202.
Can I also try lowering R3R, R3L in my 2x flat gain filter to make it a 1x?
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solderdude
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Post by solderdude on May 25, 2020 5:32:23 GMT
Yes, but only with the flat gain module.
You cannot use this trick with filter modules.
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Post by justin on May 26, 2020 9:50:19 GMT
The gain of the Kameleon is completely determined by the module, it is not determined by the amp. The gain can be 'varied' between 0.01x to 100x depending on what module you put in there. Flexible and customizable. Should one find the gain of of the 'filter modules' too high or low that filter can be designed with another gain (within limits) The Kameleon = NOT just another amplifier, but can be used as one... a bit too expensive for solely that purpose. Has the design philosophy changed to simplify things? |
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