to use a 555 timer circuit to generate a variable 1 to 5 minute timer to a lternate between 2 bank of batteries that are connected to a charger and a load. There are four switches where two are on when the other two are off. Please send me a private email to if you are i nterested and can help. Thanks!
way over my head, I still need help and would contact some of the folks who had replied and shared their contact information. Thanks again, I do appr eciate the suggestions.
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Hi Mike: I wanted to power loads without the loads seeing the battery. So, the batt eries will be connected to a charger as well as a super capacitor of equal voltage. So, the switch is to allow one battery to work while the other is on charge. I've been told this is not possible but I know wherever there' s a will, there's always a way. Thanks for your insight. I truly apprecia te it.
to use a 555 timer circuit to generate a variable 1 to 5 minute timer to al ternate between 2 bank of batteries that are connected to a charger and a l oad. There are four switches where two are on when the other two are off. Please send me a private email to if you are in terested and can help. Thanks!
oad, no batteries, timers or switches necessary.
Hi: Agree, but the charger can dump the same amp to one or more batteries at no increase in input. So, the reason for using battery bank.
e to use a 555 timer circuit to generate a variable 1 to 5 minute timer to alternate between 2 bank of batteries that are connected to a charger and a load. There are four switches where two are on when the other two are off . Please send me a private email to if you are interested and can help. Thanks!
load, no batteries, timers or switches necessary.
no increase in input. So, the reason for using battery bank.
Do you understand that batteries do not store all the charge supplied to th em by the charger? What this means is for certain battery technologies and high charging currents, the charger would have to supply up to twice the ch arge to the batteries than the batteries supply to the load. That would be called an extremely inefficient system, wasteful of energy, parts, space, a nd money, all unnecessarily.
** Back in 1977, I made myself a darkroom timer for B&W printing from negat ives in an enlarger. It was based on a NE555 monostable. A rotary switch selected resistors wired in 1:1.4 sequence, equating to sto ps on a camera. Another switch multiplied time settings by 10. The range wa s from 1 second to 450 seconds. 4x15uF tantalums provided the delay and the x10 times switch operated by pulling the voltage on pin 5 up and down for long and short delays respectively.
The OP could use switched resistors with a maximum of say 5Mohms for time s etting and a 20uF worth of film cap for delay. Then pull pin 5 towards the supply with a trim pot and resistor in series of about 1kohms each to get e xactly 300 seconds - which also calibrates the unit.
5% accuracy and repeatability should be easily had.
I'd agree that the 555 is one of the most versatile/useful devices in history. Emphasis on "history". In 1977, that solution may have been far better than the alternatives. Add up the parts cost today and compare that to a microcontroller solution.
I built a long-duration timer out of a pair of unijunction transistors. But I wouldn't recommend it today.
Based on what little we know about the application, I judge that there are a lot more issues involved in sequencing the transfer that will require additional timing functions. Bite the bullet and put in a microcontroller so you can fix stuff as you learn about those problems.
I'd still recommend going back to the system architecture and taking another look.
atives in an enlarger. It was based on a NE555 monostable.
tops on a camera. Another switch multiplied time settings by 10. The range was from 1 second to 450 seconds. 4x15uF tantalums provided the delay and t he x10 times switch operated by pulling the voltage on pin 5 up and down fo r long and short delays respectively.
setting and a 20uF worth of film cap for delay. Then pull pin 5 towards th e supply with a trim pot and resistor in series of about 1kohms each to get exactly 300 seconds - which also calibrates the unit.
Not all that adventurous for 1977. CMOS had become relatively cheap by then , so a CD4060 and a 32768 Hz watch crystal could have given you a much more accurate time base. The nice thing about CMOS was that it offered quite wi de counters in a single cheap package - 12-bits in the CD4040, and two deci mal decades in the MC1458.
Setting up the numbers was a pain. Thumb-wheel switches were big, expensive and hard to mount. Screw-driver set-able PCB-mounting miniature rotary swi tches took a few more years to show up, as did single-chip microprocessors.
I'd like to understand exactly what that means. The purpose of the battery is to supply current...What does "not seeing the battery mean?" There's gotta be a reason to justify all this complexity???
How many volts and amps are we talking about here? What's the battery technology?
So, the batteries will be connected to a charger as well as a
super capacitor of equal voltage. New wrinkle. Connected how? Why? If the voltages are equal, no current flows. If the voltages are unequal and the impedance is low, TOO MUCH current flows. If the impedance is high, efficiency suffers.
So, the switch is to allow
one battery to work while the other is on charge.
What's the motivation? Why can't you just charge the battery that's in use? If it's isolation, there may be much easier ways.
You asked for a 555 circuit and I'm lecturing you on system architecture. I predict that you'll be putting patch on top of patch on top of patch to kludge something into working. I am trying to help you avoid doing that.
I've been told this is not possible but I know wherever there's a will,
there's always a way. Thanks for your insight. I truly appreciate it.
I think you need to explain what it is that you are trying to do before it is possible to offer any sensible advice. You don't appear to have grasped even the basic concepts of how electrical circuits work!
The super capacitor is performing the same function as a battery only doing it very badly with a voltage output that falls away exponentially with time under load. I can't imagine why you would want to do that.
OK there are a few specialist things like charging up a huge bank of EHT capacitors very slowly and then letting rip discharging in a few us.
On a good day they're 0.23 ea at qty 25 in easy to use DIP packages,
That's Ok if you can spend a grand on them. you also need a voltage regulator...
CD4060 is probably the best soltion to the original problem. today singles are 25c in SOIC or a buck in DIP, I provisioned myself with DIP parts when they about 40c
egatives in an enlarger. It was based on a NE555 monostable.
stops on a camera. Another switch multiplied time settings by 10. The rang e was from 1 second to 450 seconds. 4x15uF tantalums provided the delay and the x10 times switch operated by pulling the voltage on pin 5 up and down for long and short delays respectively.
me setting and a 20uF worth of film cap for delay. Then pull pin 5 towards the supply with a trim pot and resistor in series of about 1kohms each to g et exactly 300 seconds - which also calibrates the unit.
** Actually, I *was* pretty adventurous. In order for the 555 to drive the gate of a triac for the enlarger's lamp - the whole circuit was "hot". It worked perfectly for several months and th en one evening, went BANG.
The rotary switch was not able to stand 240VAC between its metal shaft and the nearby wiper track. A post mortem revealed the clearance was barely 0.4 mm.
Version 1.1 included a HP darlington opto so one could safely ground the 55
5 part of the unit. Dedicated triac driver optos ( like MOCs ) were thin on the ground in Sydney back then - so I used a 2N4443 SCR inside a bridge an d made a non isolated DC supply for the opto.
I would agree. The OP should state in excruciating detail exactly what it is he is trying to accomplish. I suspect the thing that is going to bite him hard on the ass will have nothing to do with the core timer implementation.
then, so a CD4060 and a 32768 Hz watch crystal could have given you a much more accurate time base. The nice thing about CMOS was that it offered quite wide counters in a single cheap package - 12-bits in the CD4040, and two decimal decades in the MC1458.
You know Bill, the last I time I checked and have known for years a MC1458 is a dual op-amp... Did we slip with the data collection, again ?
I think he wants to use 2 sets of 48 volt batteries to supply 250 watts at
120VAC through an inverter while at the same time charging the second set of batteries from renewable sources such as solar and wind. He needs a system to manage that operation and also a regulator to prevent overcharge. He has implemented the system using manual switches but has limited experience with electronics. He wants someone to gather the details and assemble the circuit for a fee. If you can do that, send him a email and ask all the questions so you know what is needed. I thought the 555 timer idea might work, but it wasn't clear about the duty cycle, or changing conditions.
On Friday, 19 December 2014 11:26:46 UTC+11, Maynard A. Philbrook Jr. wrot e:
r the
negatives in an enlarger. It was based on a NE555 monostable.
to stops on a camera. Another switch multiplied time settings by 10. The ra nge was from 1 second to 450 seconds. 4x15uF tantalums provided the delay a nd the x10 times switch operated by pulling the voltage on pin 5 up and dow n for long and short delays respectively.
time setting and a 20uF worth of film cap for delay. Then pull pin 5 toward s the supply with a trim pot and resistor in series of about 1kohms each to get exactly 300 seconds - which also calibrates the unit.
No. Just anther typo.
formatting link
I'd dug out the above data sheet when I posted the commnet, so it was a sta ndard error of action - in this case a deletion.
Most people would have been able to work that out from the context.
Still no reasoning presented for using two sets of batteries. Some issues. Battery charge efficiency is less than 1. Constant charging and discharging wears them out. Taking the same number of amp-hours out of twice as big a battery wears it less and is more efficient than twice the current per cell out of each set. If you have sustainable current available, you don't need to wear the batteries to use it. If you don't have sustainable current available, you'd be better off with the batteries in parallel anyway. If you need a regulator, you have excess charge energy. Seems rational to stuff that energy into the battery being used. Then there's the whole issue of heat generated during the constant charge/discharge shortening the battery life.
I've done hardware and software architecture work for mountaintop radio repeater installations. After years of dealing with real-world issues, the recent systems just stuff the wind generator and the solar power into the batteries.
A single PIC16F877A programmed in BASIC, for historical reasons, implements the MPPT controller for the solar and the load-dump shunt regulator that clamps the battery voltage. Turns out that we had to do that to keep an unloaded wind generator from tearing itself apart in high wind...so just shunt regulate the whole damn thing. The PIC also implements the logging and voice synthesis to support reporting battery status and weather over the radio. The guys also implemented a solar tracker that moves the array to track the sun...but it was deemed too mechanically fragile to survive winter on a mountaintop and abandoned.
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