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basics | Creating a voltage-controlled resistance
There are 26 messages in this thread.
You are currently looking at messages 0 to 10.
Creating a voltage-controlled resistance - David - 2007-09-11 10:56:00
I'm testing rechargeable batteries and would like a voltage-controlled resistance so I can easily adjust the load with a program. I'd appreciate recommendations on how to design this. Thanks, David
Re: Creating a voltage-controlled resistance - Eeyore - 2007-09-11 11:13:00
David wrote: > I'm testing rechargeable batteries and would like a voltage-controlled > resistance so I can easily adjust the load with a program. Would a controlled current load be suitable ? That's a far simpler design task. Graham
Re: Creating a voltage-controlled resistance - Phil Allison - 2007-09-11 11:15:00
"David" > > I'm testing rechargeable batteries and would like a voltage-controlled > resistance so I can easily adjust the load with a program. ** Would kinda help to know a few more details. You testing AAA cells or 2.5 ton submarine batteries ?? What load power levels, what max voltage ... The * answer fairy * is on holiday and none of us hear can read minds via usenet. Get it ??? ....... Phil
Re: Creating a voltage-controlled resistance - John Fields - 2007-09-11 12:32:00
On Tue, 11 Sep 2007 10:56:30 -0400, "David" <d...@yoowhoo.com> wrote: >I'm testing rechargeable batteries and would like a voltage-controlled >resistance so I can easily adjust the load with a program. > >I'd appreciate recommendations on how to design this. --- How about numerically controlled instead? View in Courier: BAT+>------+------+ | | [128R] | | | D | IN7>-----G | S | | | BAT->------+ | | | GND>-------+---+ | | | +---|--+ | | | [64R] | | | | | D | | IN6>-----G | | S | | | | | +---+ | | | +---|--+ | | | [32R] | | | | | D | | IN5>-----G | | S | | | | | +---+ | | | +---|--+ | | | [16R] | | | | | D | | IN4>-----G | | S | | | | | +---+ | | | +---|--+ | | | [8R] | | | | | D | | IN3>-----G | | S | | | | | +---+ | | | +---|--+ | | | [4R] | | | | | D | | IN2>-----G | | S | | | | | +---+--+ | | +---|--+ | | | [2R] | | | | | D | | IN1>-----G | | S | | | | | +---+ | | | +---|--+ | | [R] | | | D | IN0>-----G | S | | | +---+ All the MOSFETs are N channel and you select the voltage, channel resistance, and dissipation depending on what kind of battery you're testing. Also the load resistances. Put a shift register on the MOSFET gates and you can control the whole thing with 3 bits of data. -- JF
Re: Creating a voltage-controlled resistance - Don Bowey - 2007-09-11 14:40:00
On 9/11/07 9:32 AM, in article a...@4ax.com, "John Fields" <j...@austininstruments.com> wrote: > On Tue, 11 Sep 2007 10:56:30 -0400, "David" > <d...@yoowhoo.com> wrote: > >> I'm testing rechargeable batteries and would like a voltage-controlled >> resistance so I can easily adjust the load with a program. >> >> I'd appreciate recommendations on how to design this. > > --- > How about numerically controlled instead? View in Courier: > Snip > +---|--+ > | | | > [4R] | | > | | | > D | | > IN2>-----G | | > S | | > | | | +---+ |<<<< had a jumper to 'S' here. > | | > +---|--+ Snip > All the MOSFETs are N channel and you select the voltage, channel > resistance, and dissipation depending on what kind of battery you're > testing. Also the load resistances. > > Put a shift register on the MOSFET gates and you can control the > whole thing with 3 bits of data. >
Re: Creating a voltage-controlled resistance - John Fields - 2007-09-11 14:57:00
On Tue, 11 Sep 2007 11:40:05 -0700, Don Bowey <d...@comcast.net> wrote: >Snip > >> +---|--+ >> | | | >> [4R] | | >> | | | >> D | | >> IN2>-----G | | >> S | | >> | | | > +---+ |<<<< had a jumper to 'S' here. >> | | >> +---|--+ > > >Snip --- YOW!!! Thanks. :-) -- JF
Re: Creating a voltage-controlled resistance - Jamie - 2007-09-11 19:03:00
David wrote: > I'm testing rechargeable batteries and would like a voltage-controlled > resistance so I can easily adjust the load with a program. > > I'd appreciate recommendations on how to design this. > > Thanks, > > David > > > > Assuming you're talking about microchip processor coding or maybe even from the PC port? You can pulse width modulate (PWM).And drive a switching device like a Power fet or bipolar transistor to regulate. Of course, you should also monitor current. This would mean a device that has either a ADC ( Analog to Digital Converter) or, use a series of voltage comparator as ranges to activate a few IO lines as inputs. There are small AVR's and PIC chips that have this ability. My self, for this, I would use an AVR. But that's my preference. Most Uc's have a PWM function in it that will use an IO or, you can make one via a timer function. I don't know where you are at the level of electronics with this? -- "I'm never wrong, once i thought i was, but was mistaken" Real Programmers Do things like this. http://webpages.charter.net/jamie_5
Re: Creating a voltage-controlled resistance - David - 2007-09-11 22:03:00
"Phil Allison" <p...@tpg.com.au> wrote in message news:5...@mid.individual.net... > > The * answer fairy * is on holiday and none of us hear can read minds > via usenet. > > Get it ??? > Hear hear! The others who have responded will be plenty of help, your pompous attitude surely has a better use elsewhere.
Re: Creating a voltage-controlled resistance - David - 2007-09-11 22:12:00
"Jamie" <j...@charter.net> wrote in message news:AWEFi.51$s...@newsfe04.lga... > David wrote: >> I'm testing rechargeable batteries and would like a voltage-controlled >> resistance so I can easily adjust the load with a program. >> >> I'd appreciate recommendations on how to design this. >> >> Thanks, >> >> David >> >> >> >> > Assuming you're talking about microchip processor coding or maybe > even from the PC port? > You can pulse width modulate (PWM).And drive a switching device like a > Power fet or bipolar transistor to regulate. Of course, you should also > monitor current. This would mean a device that has either a ADC ( > Analog to Digital Converter) or, use a series of voltage comparator as > ranges to activate a few IO lines as inputs. > > There are small AVR's and PIC chips that have this ability. > My self, for this, I would use an AVR. But that's my preference. > > > Most Uc's have a PWM function in it that will use an IO or, you > can make one via a timer function. > > I don't know where you are at the level of electronics with this? > > -- > "I'm never wrong, once i thought i was, but was mistaken" > Real Programmers Do things like this. > http://webpages.charter.net/jamie_5 > > I have a DAQ card to control the active resistance and sample the current/voltage. Plan to use a shunt resistor to monitor the current. I studied transistors in college years ago but am quite rusty. You're suggesting using PWM to control the resistance? I'd like to drain the batteries with a steady current, wouldn't that cause it to alternate?
Re: Creating a voltage-controlled resistance - David - 2007-09-11 22:15:00
"John Fields" <j...@austininstruments.com> wrote in message news:a...@4ax.com... > On Tue, 11 Sep 2007 11:40:05 -0700, Don Bowey <d...@comcast.net> > wrote: > > >>Snip >> >>> +---|--+ >>> | | | >>> [4R] | | >>> | | | >>> D | | >>> IN2>-----G | | >>> S | | >>> | | | >> +---+ |<<<< had a jumper to 'S' here. >>> | | >>> +---|--+ >> >> >>Snip > > --- > YOW!!! Thanks. :-) > > > -- > JF > I think something like this will work. I wasn't envisioning discrete levels at first but there should be no problem doing it that way. Thanks!