Help needed for regulated charging and track power for 9v sound systems

beavercreek

beavercreek

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I have been building up a cattle train with powered bogies on three cars and also fitting some of the cars with QSI digital 'Live Action' cow sound systems. The 'Live Action' cards were produced by QSI about ten or so years ago and were fitted into mainly O scale rolling stock. They have very good digital quality sounds that are played randomly but also 'controlled' by a pendulum that rocks with the sound of the car and causes the 'cows' (or other sounds for different cards) to get a little more agitated and then extra sounds are heard as the cows feel the bucking of the car.

Well, these cards are powered by a 9v PP9 battery and I would like to have them powered from the track as well as the 9V rechargeable battery for when track voltage is below that which the card needs to operate or if there are 'gaps' in track pick-up.
In order to have this operational would I be correct in assuming that there would have to be a voltage regulator to keep the voltage going to the card never over 9v and I would have to have a form of bridge to make sure that polarity going to the card and the battery is always correct no matter which polarity is available on the track (it is DC at the moment)?

I would like the battery to be able to charge at the track if possible whilst the cars are in use and also have a charge jack to charge from the bench. This is much like Phoenix and Soundtraxx cards use their back-up battery.

Also I would need to include a switch to switch the power to the sound card off whilst charging but this could be accomplished by the charging jack internal pressure switch.

My knowledge with electronics is limited but I do understand diagrams...I think
In my unfinished diagram I have the basic components but the circuitry of the power regulator and polarity circuit and connections are defeating me.
Please help a dullard........................

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The box in the middle of the diagram is where the valued help from my fellow members would be put to use to show the regulator and polarity circuitry.
 
I have had contact from one member of the forum which will definitely proove to be ultra useful. I would also like as much input as possible, just in case one member's ideas do not totally overcome the possibilities.
 
This may not be much help, but can I suggest you just forget it and run the sounds from the rechargeable battery only.

I've been down that path. For a start, it's hard to build a 'good' battery charger in. You build the complicated electronics, and the thing runs nicely and sounds great. But you don't remember to clean the wheels and it stops charging the battery anyhow. But you don't know that because the sounds are still running nicely on the battery. And the battery goes flat anyhow. You might as well just keep it charged up on the bench. If it's not running long enough on your small 9V battery, get a bigger capacity. Six NiMH would probably work giving around 8V.

For my first couple of battery powered locos I did what you are thinking, but finaly ripped all the circuits out.
 
Hi Greg
Many thanks for the input.
I was thinking that you may be right, but what is keeping my hopes up, is that I have quite a few locos with Soundtraxx (uses 6v back-up) and Phoenix (uses 3.7V back-up) sound system cards and these work on the process of track power down to a certain voltage (between 5 and 8 V) where the back-up battery kicks in for low speed and standing sounds for up to 30 secs. The batteries charge from the track via the cards after the voltage reaches above 8 volts or so while they are rolling around. This does work as I have tested batteries before and after a good 3 hour run.

I was thinking that my OSI stockcar 9v cards would be able to power/charge etc., the same as the Soundtraxx and Phoenix ones do, but whereas these sound cards have the charging function built in, the QSI ones will need this to be made up and wiring configured.

I do see your point that just bench charging would be a lot simpler but as there are presently 3 cars with these cards and possibly up to 5 the taking out and charging of batteries might be a little fiddly and time consuming and as I have deatiled and weathered these cars I really do want to keep the handling of them to a minimum.
Charging on the track while they are in use with the option of charging from a jack does give that 'ease of use'.
I will be using either LGB ballbearing pickup wheels or the AML variety with the same function.

But I have a feeling that your words of wisdom may win out......I will keep you posted!
 
I use a RAM #59 9 volt regulator to keep the battery charged in my LGB sound boxcar. Don't know the availabilty in the UK, but this is available from ramrcandramtrack.com in the U.S.

---Hutch
 
I have had a bit of a think with my little brain and have come up with the diagram below. I think that the bridge rectifier is okay but it could be way off and cause shorts all over the place and I do not know the ratings of the diodes (could be IN1400 or I could use a ready made rectifier component) and capacitors 25 V 220F and 0,1f 25V but it seems to give the following using DC analogue or DCC:

1) constant polarity no matter what is coming from the track
2) regulated voltage at 9v
3) ability for the battery to be used as back-up in the event that track power is interrupted or car is at rest.
4) ability to use track power or jack to charge battery

BUT I am little experienced in creating more complex circuits like this (I know some of you will think that this is a very simple jobbie) and I could easily have made glaring errors.
If this is a goer I would be grateful for any pointers as to the values of the components ie the diodes capacitors and regulator to be able to work at the voltages and amps that occur on DC (or DCC) track.

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beavercreek said:
Hi Greg
Many thanks for the input.
I do see your point that just bench charging would be a lot simpler but as there are presently 3 cars with these cards and possibly up to 5 the taking out and charging of batteries might be a little fiddly and time consuming and as I have deatiled and weathered these cars I really do want to keep the handling of them to a minimum.
Charging on the track while they are in use with the option of charging from a jack does give that 'ease of use'.
I will be using either LGB ballbearing pickup wheels or the AML variety with the same function.
But I have a feeling that your words of wisdom may win out......I will keep you posted!
Click to expand...
Good luck!
Now refering to your circuit, I did a few bench tests using a 5V regulator and battery (NiMH). As I suspected, the battery will feed back into the regulator when you have no input to regulator. ie when no track power high enough. About 5mA in my case. But enough to flatten a battery over time. So you'd need diode D1 or a 2nd on/off switch pole?. This reduces the voltage to load but you could compensate with D3.
The next problem is that there is nothing to limit the charging current into the battery if it's 'flat' or low. So You'd need D2 and R. Now you only have 9V-0.6 of the diode when running on battery. The value of R will depend on the capacity of your battery and it's actual voltage. And you can never charge it to more than the 9V+0.6V of the regulator (and D3), which may not be enough to get anywhere near full charge.

So it will take a bit of work to get it to be useful.
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BTW, why do you have to take the batteries out to charge?
 
Wow, thanks Greg that seems to cover the bases. I would use a switch to switch off the whole assembly so I would use a DPST to cut supply to battery and card...... and I can see the need for the diodes to stop feedback into the regulator.
I am meeting Neil (Robinson) at the show and he has come at the solution another way to me, so it will be good to see his ideas. You have managed to make my idea workable but perhaps it was not the best idea to start with!!

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If I kept the switch by the battery, as it it operates with the the one by the card and thus cuts all connections from regulator to card and battery in one action, would that not be okay...or...do I need to have the D2/R components to stop battery feedback during the charging from the track when the switches would be closed? Wouldn't the check diodes by the regulator stop this 'feedback' anyway?
As you can see Greg I am at the limits of my knowledge here.

Also I included capacitors but perhaps they will only be useful for when track is AC (DCC)

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beavercreek said:
If I kept the switch by the battery, as it it operates with the the one by the card and thus cuts all connections from regulator to card and battery in one action, would that not be okay...or...do I need to have the D2/R components to stop battery feedback during the charging from the track when the switches would be closed? Wouldn't the check diodes by the regulator stop this 'feedback' anyway?
As you can see Greg I am at the limits of my knowledge here.
Also I included capacitors but perhaps they will only be useful for when track is AC (DCC)
Click to expand...
The D2 & R components MAY not be necessary, so you could have the switch on the battery as you show. BUT you might not get much charge into the battery with exactly 9V from the regulator as batteries are usually higher voltage than their nominal (9V). On the other hand, if the battery is very flat, you might gets a high current into the battery from the regulator/track. Hard to say - best to give it a go without D3 & R.
I had noticed the capacitors. The 0.1 on the output is a recommended necessity. I'm not sure the 220 uF will achieve anything.
Don't forget you'll need about 11V on the track before the regulator 'regulates'!
I'm assuming you're using a 7809 regulator

Just as aside, and for others' information about regulators - . These 78xx series are good workhorses - the xx just represents the voltage - you can get 7805, 7806, 7809, 7810, 7812 and 7815 that I know of.
They have just 3 terminals as shown here.
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Now the interesting thing is you can adjust the output voltage easily. The COM connection to the device carries very little current, so you can use circuits like these to change the voltage. Just choose R1 about 1k and R2 to suit what you want.
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Thanks again Greg.
I included the caps as I had gleaned that you need these for when smoothing AC input. But at the moment I run DC BUT will probably be going over to DCC (for all or one section of my layout), so I presumed that that I should include both caps for when DCC is used (for the AC voltage) but that the 220F is really superfluous for DC..Am I right here...is the 220F not needed or should it just be lower value for DC input?

Yeah, I was unfortunately aware that the regulator will only kick in at about 11 volts, so the charging circuit voltage and voltage to the board from the track will only be delivered at that 11V and above. My Soundtraxx and Phoenix boards have batteries of 6V and 3.6V so their built in regulators are working at much lower voltage and therefore their batteries charge at about 5V or 8V respectively.
Unfortunately the 'QSI Live Action' cards are 9V so this does give me a little bit of a dilemma as the battery charging and card will be only working above about 11V from the track and so to make sure that there is enough voltage for the regulator to work, first I will need to test how much voltage is being delivered from the wheels of the stock-cars when the whole train is travelling at the speed that I want it to travel at (which will not be fast but more prototypical).
I think that the 11V threshold might just be okay for a train of three locos (Bacchmann Annies), three motorised stock-cars (Aristo centrecab blocks), 9 more stock cars and also the 3 or 4 sound cards with the whole lot climbing the inclines of my layout, so it is likely that the regulators will be out-puting voltage to battery and card. Of course shorter less 'complex' trains might mean that the voltage is not high enough for the regulators to work and the battery will be doing all the work and need to be charged at the bench!
 
beavercreek said:
Thanks again Greg.
I included the caps as I had gleaned that you need these for when smoothing AC input. But at the moment I run DC BUT will probably be going over to DCC (for all or one section of my layout), so I presumed that that I should include both caps for when DCC is used (for the AC voltage) but that the 220F is really superfluous for DC..Am I right here...is the 220F not needed or should it just be lower value for DC input?
Click to expand...
Data sheets for 78xx require the 0.1uF on output. I don't think there's any harm in including the 220uF but I have this vague recollection from years ago that you shouldn't use a big C on the input. Can't remember why and a quick look at data sheet doesn't bring it up. Maybe you can peruse.

DON'T FORGET THE REGULATOR IS GOING TO GET HOT AND WILL NEED A HEATSINK. Again look at the datasheet (google 7809 datasheet)
 
Thanks for the info on regulators. I was going to screw the regulator to a block weight in the car.

On the subject of the larger capacitor inclusion, I found this circuit at the beginning of all my investigations. It is really a 9V output transformer that is working with 16V down from 240V but the bit from 16V is very similar to what I want to do but it obviously does not have the cutoff switches and diodes to stop back leakage. It, like others of its ilk, have a large capacitor which I think is to charge to the full voltage for the regulator even at low voltages (in my case from the track)
I know that there needs to be 'smoothing' when transforming 240AC down to 9V or similar DC voltages so I imagine the large cap is helping in that function too.
As you say it will need a little more delving.


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beavercreek said:
Thanks for the info on regulators. I was going to screw the regulator to a block weight in the car.
On the subject of the larger capacitor inclusion, I found this circuit at the beginning of all my investigations. It is really a 9V output transformer that is working with 16V down from 240V but the bit from 16V is very similar to what I want to do but it obviously does not have the cutoff switches and diodes to stop back leakage. It, like others of its ilk, have a large capacitor which I think is to charge to the full voltage for the regulator even at low voltages (in my case from the track)
I know that there needs to be 'smoothing' when transforming 240AC down to 9V or similar DC voltages so I imagine the large cap is helping in that function too.
As you say it will need a little more delving.
Click to expand...
I was obviously having a 'seniors moment' when I referred to no capacitors on the input. The data sheets specify that big caps on the OUTPUT are a no, no. And you are correct in that your cct is nother more than any other mains power supply. So go ahead and put as big a cap as possible on the input - if you can fit in 2200 uF do it. Make sure its working voltage rating is higher than your track voltage.
 
Hi Greg
I met Neil on Sunday at the G scale Society show and we discussed at length the circuit and what would be best. Neil brought to light some things that need to be borne in mind when constructing trickle chargers.
So we agreed that it would be best to go ahead with my initial design for the regulated/polarity protected voltage supply to the card which also includes the option of powering the card from the battery at low track voltage and to include the charging jack....... BUT..... to keep the construction of the on-board 'trickle charger' part of the circuit until later when the the initial circuit is proven to work. As the construction of the trickle charger will need a bit of tweaking depending on testing for voltage drop across the components so that the potential differences are correct, this does make a lot of sense.

The working 'simpler' part will mean that I will have the function of the card powered from the track (with battery back-up) and also the ability to charge the battery in situ and it will not have to be removed so that handling of the weathered and detailed cars is kept to a minimum. And I am very happy with that, but the 'trickle charger' circuit will be designed and built, then tested with one of the main sound card circuits (the components in both circuits will have an effect on the current/voltage levels) and amendments made if needed.

I will post the diagram of the 'trickle-charge circuit diagram when I actually get around to building that part!

Many thanks again for your input Greg and I would be very grateful if you give more thoughts when I post the future 'trickle charger' circuit efforts.

I have found this circuit which is a nimh trickle charger for 9v-12v batteries. It would not need the polarity protection part as this would be there already and the led might not be important...I wonder if it could be integrated???? Would low voltage input (below about 11V) just cause the trickle charger to be not active...perhaps an inverter could be included to be able to utilise low voltage..........ooh my head hurts :@&:

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beavercreek said:
I have found this circuit which is a NiMH trickle charger for 9v-12v batteries.
Click to expand...
With respect I fear you may have misread the description of that circuit, it states "The charger provides 140mA for quick charging of the battery".
I would suggest one tenth of that current for a trickle charge would be better for your application.
 
Yeah Neil, I must admit that I added the 'trickle' charger' circuit as a quick edit to my post and I skim read the description. If the 'fast charger' auto stops charging when the battery is fully charged would it be okay or should I stay with a 'trickle charger'
 
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