AC-to-DC adapter for controller

gRC · #1 10-04-2002, 11:57 AM

I mod'ed my ZipZaps controller last night to use an AC-to-DC adapter. Basically I opened the controller by removing the screws, drilled a 5/32" hole next to the left side of the battery compartment, and mounted a 3/32" (2.5mm) submini jack (Radio Shack part #274-245). I am using an AC-to-DC adapter rated at 3V and 200mA with a submini plug (#273-1708, Adaptaplug E). For safety I remove the batteries before plugging the adapter into the controller.

This mod seems to be working well. The controller has the same range as before (if not better), and the car is fully charged in the same amount of time. Furthermore, its performance will most likely be more consistent because there is no battery drainage to worry about.

I may post pics and more detailed instructions later if there is interest.

One question: Would there be any benefits in using an AC-to-DC adapter that has a different rating for voltage and/or milliamps? Or are 3V and 200mA really good enough?

JediYoda56 · #2 10-04-2002, 12:14 PM

Now if you could do a AC-to-DC adapter for car for the car that would be awesome. Limted range but think of the power!

haha

Namuna · #3 10-04-2002, 12:23 PM

Yet again the gRC comes through with the goods!

As far as voltage/amperage goes...I'd say you're dead-on for the voltage at 3v (since it takes 2x1.5 in series AAs).

I'd think you could probably go higher than 200mA though, but the only way to be really sure is to pull out the trusty MultiMeter and check the current with the standard AAs and go from there.

Good work gRC!

Axel · #4 10-04-2002, 01:20 PM

I've been wondering this too... would it help the controller to put more than 3V into it? It makes the car go faster, so would it make the controller throw a stronger signal?

Has anybody tried putting more juice through the controller yet?

gRC · #5 10-04-2002, 01:50 PM

Quote:

Originally posted by Namuna
I'd think you could probably go higher than 200mA though, but the only way to be really sure is to pull out the trusty MultiMeter and check the current with the standard AAs and go from there.

I have not tried the multimeter yet, but I have noticed that the red LED is dimmer when charging if I use the adapter instead of fresh AAA batteries. So I probably could use an adapter that has more milliamps.

Nightwing · #6 10-04-2002, 03:00 PM

Maybe this will help.

A standard set of AA battries should give you around 450ma. Not sure but I think AAA should be around 300 to 400.

Namuna got it right. Grab a fresh set of battries. Measure just idle current. The measure charging the car. Also note voltage level doing both.

Unless that has a regulator in it, most wall/floor warts transformers consist of a step down transformer one to four diodes and a filter cap. IE they dont have constant voltage for 0 to max current and a nasty ripple. Sometimes I have seen 2 to 5 volts higher on light load. The voltage is normal what is rated when at or near the rated current.

May want to get a higher voltage and regulate it down to 3v. This will clean up the voltage and make it more like a battery.

Namuna · #7 10-04-2002, 03:09 PM

Ooof, good point about the 'ripple' NW!

What do you suggest as a means to regulate a higher voltage adapter down to 3v?

Nightwing · #8 10-04-2002, 04:36 PM

RS sells a adjustable one #276-1778 can hit 3 v and regulate about 1 amp. Takes one or two fix resistor, a pot and two caps. I recomend some electrolitics over the disk caps they show. Around 100mf on output and same on input or something close. Since you want 3v out should feed it with about 4.5 to 5 or more. If you feed it with more than that add a heatsink to let it get rid of some of its heat it will burn off to get it down to 3volts.

brianpipa · #9 10-04-2002, 06:14 PM

I was just thinking baout this today. Yes, PLEASE post detailed instructions so I can do this too!

brian

Nightwing · #10 10-04-2002, 10:39 PM

Hum... RS does not sell a decent size heat sink any more!

Could use some PC board copper as the ground and heatsink. I have almost all the componets in stock but want to get some RS same parts to make it easy to duplicate.

Also notice that RS has a 3v 700ma filtered and regulated adapter for 14 dollars. Will grab one and check it out but will come up with a simple list and instruction on a filter for a unregulated one.

gRC · #11 10-05-2002, 04:18 PM

I picked up several 3V adapters from Radio Shack to try out. They are candidates to replace my seemingly inadequate 3V 200mA adapter.

I first used my digital multimeter to measure the voltage and amperage of a fresh pair of AAA batteries in the controller. When the controller is turned on but not charging, the batteries produce 3.00V and just 7.5mA. When the controller is charging the car, they produce 2.48V and possibly over 200mA. My multimeter cannot measure amperage over 200mA, but it would occasionally display measurements in the range of 190mA to 199mA, which may or may not be significant.

The table below shows the voltage measurements for the various AC-to-DC adapters. The fields are as follows: voltage when not charging, voltage when charging, Radio Shack part number, price, voltage and amperage rating.

3.66V 1.92V 273-1661 $XX.XX 3V 200mA
3.19V 2.44V 273-1667 $15.99 3-12V 800mA
3.20V 2.82V 273-1756 $16.59 3V 700mA
3.18V 3.02V 273-1754 $19.99 3V 1000mA
3.14V 3.00V 273-1695 $19.99 3-6.5V 2500mA
3.83V 2.58V 273-1755 $13.99 3V 500mA
4.04V 2.20V 273-1662 $14.99 1.5-12V 300mA

I noticed that the red LED looked different depending on which adapter was being used for charging. With the 200mA adapter it appeared dimmer than usual. With the 700mA, 1000mA, and 2500mA adapters it appeared orange instead of red because the green LED was slightly lit at the same time. With the 800mA adapter it appeared the same as with the AAA batteries. Therefore, it seems that the appearance of the red LED is related to the voltage when charging. However, I am not sure if it is better or worse to have a charging voltage that is lower, higher, or the same as that of the batteries. I assume that having nearly the same charging voltage would be ideal, as is the case with the 800mA adapter. One advantage of the 800mA adapter is its variety of voltages for other devices, but one disadvantage is that it is the largest and heaviest of the adapters.

If someone is able to measure the actual amperage when charging, I would be interested in that measurement.

I plan to post pics and detailed instructions of the mod later.

Edit: I measured two more adapters and added their voltage measurements to the table above.

gRC · #12 10-06-2002, 03:41 AM

For what it's worth, I replaced the regular Duracell batteries with a fresh pair of Duracell Ultra batteries and measured the voltage again. When the controller is turned on but not charging, these batteries initially produce 3.16V and then gradually drop to around 3.0V as they are being used. When the controller is charging the car, they initially produce around 2.8V and then gradually drop to around 2.5V.

Nightwing · #13 10-06-2002, 03:23 PM

Drop my little friend on a adjustable bench supply. Wow that thing draws current! It went to about 750ma at around 2.87v while charging. Sheech!

Q4 is getting a workout!

Just for giggle here are the spects on Duracell stock Alk battries:

AAA
http://www.duracell.com/oem/Primary/Alkaline/mn2400.asp

AA
http://www.duracell.com/oem/Primary/Alkaline/mn1500.asp

I think that a std set of battries wont do 750ma. Both on voltage drop and that much current being drawn. Need to pop a line and measure.

Looks like the 800ma 3v will go back and need to design a pritty good heatsink for the adj regular version. At least it can take 1.5amp max.

gRC · #14 10-06-2002, 04:55 PM

I created a web page with several pics of the mod.

AC-to-DC adapter mod for ZipZaps controller

Nightwing · #15 10-06-2002, 06:16 PM

Nice job.

RS does offer a Coaxial DC Power Jack with switch. This allows you to keep a set of battries in the unit but when you plug in with an adaptor it cut out the battries and switches over to the adapter for you. It also makes it hard to pull out, more robust, does not short the adapter pluging and unpluging and give better contact.

If you go with this, use 274-1583 for the jack 273-1717 for the adapter on the transformer. Or whatever combo fits well. The jack is a case mounted one so you only need to drill a hole.