The first mod I'll do on the mixer won't be batteries but INSERT jacks hence this new blog:
Insert jacks for the 402-VLZ3
After completing it I'll tackle the battery power add-on and case redesign.
Battery powered Mackie 402-VLZ3™ project
My motivations: to have fun hacking hardware and to ease access for indie creators and student communities to high quality tools at low cost. The modest but thoughtful mods I'm working on (INSERT jacks, battery power supply and case redesign) will appeal to small bands, home recording musicians and hd-dslr videographers.
Saturday, February 5, 2011
Thursday, January 27, 2011
We have a winner!
Well I found at Hobby King (a Hong Kong retailer specialized in RC, Radio Control toys) a 800 mAh NiMH AAA for 0.80 USD (a low self discharge type even!) This makes a NiMH setup affordable: for 24$ I bought 30 AAA's to build two 18V packs. They will feed the two voltage regulators giving internal ±16V.
Sunday, January 16, 2011
Back to the drawing board
Well, je n'avais pas encore quitté la planche à dessin!
Researching DC-DC chips I learned that 85% efficiency is really hard to obtain: you have to optimize components (inductance, condensators, etc..). As low as 60% is not uncommon... (watch EEVblog #110 @30min)
This is not acceptable for a portable solution: carrying a bulky battery pack mainly to heat your case?
So I won't finally use a DC-DC converter for main voltage (we'll see for phantom): I'll stack LiPo or LiFe cells to go up to the ~16V dual voltage rail and regulate it off the Mackie board with a zener + emitter follower regulator (as this one ?).
Researching DC-DC chips I learned that 85% efficiency is really hard to obtain: you have to optimize components (inductance, condensators, etc..). As low as 60% is not uncommon... (watch EEVblog #110 @30min)
This is not acceptable for a portable solution: carrying a bulky battery pack mainly to heat your case?
So I won't finally use a DC-DC converter for main voltage (we'll see for phantom): I'll stack LiPo or LiFe cells to go up to the ~16V dual voltage rail and regulate it off the Mackie board with a zener + emitter follower regulator (as this one ?).
Saturday, January 15, 2011
Power struggle
Sure the cheapest and simplest way to power the 402 is with disposable AA batteries: 16$ each shot of 12 hours. But after two or three iterations, rechargeable batteries are more economical and eco-friendly.
The toughest choice is between NiMH and LiFePO4. They both cost around 4-5 $ for each hour of autonomy. Prioritizing economy, I'd go with the 6.6V LFP pack with DC-DC converters.
The toughest choice is between NiMH and LiFePO4. They both cost around 4-5 $ for each hour of autonomy. Prioritizing economy, I'd go with the 6.6V LFP pack with DC-DC converters.
Numbers
The design so far: one 26$ 4.5Ah 2S2P LiFePo4 Pack (6.6V OCV, 6.2V under load, delivering 28 Whr for 5 hr autonomy) and
three MC34063A used as step-up DC-DC converters and inverter:
- 6.2V -> + 17V@120mA
- 6.2V -> - 17V@120mA
- 6.2V -> + 48V
Wednesday, January 5, 2011
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