See the right side in the 12v power area. For the 78L05 voltage regular of 5 Volts. Why is the source voltage 12v?

Can you use 9V source? With the 78L05 150mA requirement. What is a good source of rechargeable battery to use? I will use 2 pc to get the negative rail. I don't want lead acid battery because it can explode if the charger would become defective.

 

Why is the source voltage 12v?

It uses 12V because it is there and probably something uses the 12V.
A LM78L05 can use 9V.

 

It uses 12V because it is there and probably something uses the 12V.
A LM78L05 can use 9V.

It may use 12V because besides AC, it can use car battery as source as it has adaptor for it. But I don't want to use car battery.

What other rechargeable batteries can power it? Is there a 9V powerbank?

 

The LM78L05 can operate from less than 12V, but since the input pin is labeled as 12V, there may be other parts of the board that may not.

 

Can you use 9V source? With the 78L05 150mA requirement.

9 volt yes but the 78L05 is only rated up to 100ma.
The dropout voltage is 1.7 volts so a battery voltage above 7 volts is feasible suggesting a 2C Lipo battery.

 

A Lithium-based-Battery is far more dangerous than a Lead-Acid-Battery or a Sealed-Lead-Acid-Battery.

A Lead-Acid-Battery requires extremely severe abuse before it becomes "dangerous",
quite the opposite of a Lithium-based-Battery.
.
.
.

 

9 volt yes but the 78L05 is only rated up to 100ma.
The dropout voltage is 1.7 volts so a battery voltage above 7 volts is feasible suggesting a 2C Lipo battery.

A 2C Lipo battery sounds good. It's compact enough. What do you say about using 8 pcs of 1.2V 2500mAh NiMH Eneloop batteries to produce 9.6V? But this seems so bulky but so tested already. What is the advantage of 2C Lipo vs 8 pcs of NiMH besides compactness?

Can 2C Lipo explode if the charger has problem? At least NiMH doesn't explode. What other choices?

 

Yes size. Do you need 2500 ma?
Depends on how the charger fails.
Of course anything can happen but I would say very rare. Think of all the smart phones in the world using lipo batteries that are charged every day.
Use a quality charger and forget about it.

 

Yes size. Do you need 2500 ma?
Depends on how the charger fails.
Of course anything can happen but I would say very rare. Think of all the smart phones in the world using lipo batteries that are charged every day.
Use a quality charger and forget about it.

There are 4 channels with 4 pcs of 78L05 in each pcb so the total amperage in the multichannel unit is about 400mA. With the 2500mAH.. So I guess I'll get about 2500/400=6 hours.

If I'd get the 2C Lipo 7.4V. can i get 2 pcs and put them in series and tap the middle to acquire 7.4V and -7.4V. Is this method valid for all batteries, meaning without exception, you can use the method of tapping the center to acquire the negative in all batteries?

What is the most reliable 2C Lipo brand and charger for it?

 

If I'd get the 2C Lipo 7.4V. can i get 2 pcs and put them in series and tap the middle to acquire 7.4V and -7.4V

Yes, any batteries can be used that way.

But the board shows + and - 12V inputs. (just looked at it now). Are these RS232 boards?

 

Yes, any batteries can be used that way.

But the board shows + and - 12V inputs. (just looked at it now). Are these RS232 boards?

It is an ECG unit.

The 3S lipo is 11.1V. So I think i'll get the 11.1V instead of the 2S Lipo 7.4V. So any component that needs 12V can work with 11.1V, right?

Also I noticed there is the 25C or 45C meaning the ampere delivered 25 times the capacity. But if I only need 400mA in the 2200mAh. How would 25C help?

Lastly, all lipo charger can shut down automatically or are cheap charger manual?

 

After reading the following I cancelled my 3S LIPO order. It is the most dangerous rechargeable battery that can cause fire. So with LIPO out of the way, any substitute besides the safer NIMH? What is as safe as NIHM but you don't have to use 10 cells to get 12V for the 1.2V each cell?

An Expert's Guide to Understanding LiPo Batteries — Roger's Hobby Center

"LiPo batteries offer plenty of power and runtime for us radio control enthusiasts, but that power and runtime comes at a price. LiPo batteries are capable of catching fire if not used properly - they are much more delicate than the older NiMH/NiCd batteries. The problem comes from the chemistry of the battery itself.

Lithium-Polymer batteries contain lithium, an alkali metal, which reacts with water and combusts. When heated, Lithium also combusts when reacting with oxygen. The process of using the battery, in the sometimes extreme ways that we do in the R/C world, causes there to be excess atoms of Oxygen and excess atoms of Lithium on either end (the cathode or anode) of the battery. This can and does cause Lithium Oxide (Li2O) to build up on the anode or cathode. Lithium Oxide is basically lithium corrosion, or lithium “rust”. The Li2O causes the internal resistance of the battery to increase. The practical result of higher internal resistance is that the battery will heat up more during use."

LiPo battery explosion. - YouTube

 

I use 12V SLAB (sealed lead acid battery).

 

The unit will be put in a lab. SLAB can leak sulfurid acid when it explodes. The 3S LIPO is even more dangerous as it has the same chemistry of cluster bombs. The Israeli can even turn it into exploding weapon in the pagers and walkie talkies. So I guess the NiMH is the only safe possibility?

 

If you are that worried about it then just use non rechargeable batteries.

 

I have used and abused 12V SLABs and never had one that leaked.

 

The AD AMP01 is low noise high precision instrumentation op amp probably needs the +/-12V
with the multiturn pots there is some very sensitive and precise action. The chip is capable of outputting +/-10V 50 mA
could be less but is for something very precise. The 5V supply is not nearly as precise could be alot of things
logic level. Because it uses sensitive well trimmed instrumentation I would stay with the original battery plan.

 

The AD AMP01 is low noise high precision instrumentation op amp probably needs the +/-12V
with the multiturn pots there is some very sensitive and precise action. The chip is capable of outputting +/-10V 50 mA
could be less but is for something very precise. The 5V supply is not nearly as precise could be alot of things
logic level. Because it uses sensitive well trimmed instrumentation I would stay with the original battery plan.

Yes the unit spec says the output range is +-10V. You mean if the 78L05 voltage regulator is 5 Volts and powering the AMP01 directly, its output will only be +-5V and not +-10V? Also there is only one 78L05. Can it reduce both the -12V and +12V source to -5V and +5V?

If I'd use 10 pcs of 1.2V NiMH. The final voltage will not be 12V but more like 14.5V. Will it work? In Sealed Lead Acid Battery or car batttery. Is the output exactly 12.0 if it is not being charged?

 

Hello,

The 78L05 is an 5 Volts positive regulator.
The 79L05 is an 5 Volts negative regulator.

Bertus

 

Hello,

The 78L05 is an 5 Volts positive regulator.
The 79L05 is an 5 Volts negative regulator.

Bertus

It doesn't have a 79L05. Any possibility the following circuit can produce the negative -5V rail? The transistor below the capacitor is a 2N2907. What does the portion of the circuit do? recognize the combinations? See first message for the other or whole pcb views.