How to supply power to the arduino ?

[barak198]

Hi everyone  I am building a project that include a sollar battery charger and led driver(1w *6 ) for my entrance.

Both are arduino controlled, the charger is working fine and led drivers seems easy to bulid


my qustion is that :

If I power the  arduino through a voltage regulator that it's ground is the sollar panel negative , on day light  the charger is ok  but
when it's dark the voltage regulator will not work since the regulator has no  current path .

so I thought maybe I shuold connect the regulator ground to the negative side of the battery but then the circuit won't work
because then the "ground" for the regulator is ~4V and the arduino zero output is 4V minimum.
I hope you will understand my explanation

here is the charger circuit (the led is actually the battery )
thank you all

http://www.falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+10.20027730826997+64+5+50%0At+496+192+544+192+0+1+-13.408562101316981+0.1849097844273214+100%0At+576+272+608+272+0+1+-13.593471885744302+0.0018491092549078219+100%0Ad+688+352+688+160+1+0.805904783%0Ar+480+272+528+272+0+7000%0Aw+496+192+464+192+0%0Aw+464+192+368+192+1%0Aw+464+192+464+272+0%0Aw+464+272+480+272+0%0Aw+528+272+544+272+0%0Aw+544+272+544+208+0%0Aw+544+272+576+272+0%0Aw+544+176+544+160+0%0Aw+608+256+608+160+1%0Ar+544+352+608+352+0+70%0Aw+544+160+608+160+0%0Aw+608+160+688+160+0%0Aw+544+352+544+272+0%0Aw+608+352+608+288+0%0Aw+608+352+688+352+0%0Aw+608+352+608+384+2%0Aw+608+160+608+96+2%0A172+48+80+48+48+0+6+0.2+5+0+0+0.5+Voltage%0Aw+48+80+48+128+0%0Ax+405+210+437+213+0+15+base%0Ax+631+115+650+118+0+15+col%0Ax+566+390+594+393+0+15+emit%0Aa+80+176+192+176+1+15+-15+1000000%0Aw+48+128+48+160+0%0Aw+48+160+80+160+0%0At+240+176+304+176+0+1+-16.77308814333255+0.48480134043392753+100%0Aw+304+160+304+96+0%0Ax+572+238+649+241+0+24+TIP122%0Ar+304+192+368+192+0+500%0Aw+192+176+240+176+1%0Aw+80+192+80+256+0%0Aw+80+256+304+256+0%0Aw+304+256+304+192+0%0Ar+608+384+608+432+0+1%0Ag+608+432+544+432+0%0A162+432+96+608+96+1+12.85+1+0+0%0AR+224+64+224+16+0+0+40+18+0+0+0.5%0Aw+304+64+304+96+0%0Aw+304+96+432+96+1%0Ax+371+72+644+75+0+14+Bat+simulation+:+12.8+Fwd+Voltage+at+charge%0Ax+73+55+178+58+0+24+Arduino+V%0Aw+368+192+368+288+2%0Ad+224+64+304+64+1+0.805904783%0Aw+304+64+304+32+0%0Aw+304+32+816+32+0%0Aw+608+432+816+432+0%0Aw+912+192+992+192+0%0Ax+816+55+947+58+0+24+V++regulator%0Ax+909+225+938+228+0+24+5V%0Ax+780+407+956+410+0+24+ground+regulator%0Aw+816+32+816+160+0%0Aw+816+432+816+240+0%0Aw+768+176+880+176+0%0Aw+880+192+880+224+0%0Aw+880+224+768+224+0%0Aw+768+224+768+176+0%0A

[homebrew]

Please provide a working schematic ... your web-tool does not seem to work.

[Seekonk]

I can barely see without my glasses, but that looks just wrong.  Very colorful though.

[barak198]

what seems wrong ?

[rdl]

Please provide a working schematic ... your web-tool does not seem to work.

I'm pretty sure that site requires Java (not JavaScript). Most browsers disable Java by default because of known security issues.

[mikro]

This is screencap from the site OP provided.

[rdl]

The voltage regulator input needs to be connected directly to the battery positive. The regulator, battery, solar panel and Arduino need to share a common ground.

[barak198]

is that the only way?
this charging circuit is a "current sink"

[barak198]

can anyone add a better circuit that is basicly a voltage controlled current source ?
I want to control a 3 stage charging

[rdl]

is that the only way?
...

Probably not, but I'm pretty sure it would work.
Without an accurate and readable schematic, it's not really possible to get the best of advice.

[Zero999]

can anyone add a better circuit that is basicly a voltage controlled current source ?
I want to control a 3 stage charging

A Howland current pump?

http://www.ti.com/lit/an/snoa474a/snoa474a.pdf
http://www.edn.com/design/analog/4430167/Op-Amp-Current-Sources--The-Howland-Current-Pump
http://electronicdesign.com/power/whats-all-current-source-stuff-anyhow

[Kalvin]

Something like this might do the trick:

https://e2e.ti.com/support/data_converters/precision_data_converters/w/design_notes/3156.can-the-current-output-of-these-devices-sink-current

The schematics shows the basic concept, and you need to add few capacitors for the loop stability.

See this application note, figures 19 and 20 for the further circuit explanation:
http://www.ti.com/lit/an/sboa046/sboa046.pdf