Anyone know of a simple way [without having to visit RS etc], to drop 17v AC off the back of an HO DC transformer [the accessories side of things], down to around 5 to 10v AC?
Thanks
Tanked
TankedEngine Anyone know of a simple way [without having to visit RS etc], to drop 17v AC off the back of an HO DC transformer [the accessories side of things], down to around 5 to 10v AC? Thanks Tanked
The "without visiting Radio Shack" provision would really depend on what you have on hand. To drop AC voltage, you'd need at least two resistors, or a step down transformer.
What are you using the lower voltage for? What components do you have on hand?
You can put 2 items in series with similar resistances. Each will drop 8.5 volts. But if these are light bulbs, if one blows, the other stops working. Putting the 2 motors in series instead of parallel in a 2 motor 3 rail O locomotive is sometimes done to reduce the speed of the locomotive.
If you use series resistors to drop the voltage, you need to know the current draw of the device to calculate the size and power ratings of the resistor.
You can also use a Variac in front of the power pack to regulate the AC output voltage. Note that this will also impact the DC output voltage in the same proportion.
Fred W
fwright What are you using the lower voltage for? What components do you have on hand? Fred W
I have an HO Marklin Loco that I want to hook up on alligator clips to get the motor ticking over. I don't run Marklin AC track. I have been told I need about 5v to 8v AC to start the motor. The closest I can get with current equipement is the 17v AC off the back of the HO DC power pack & prefer try a lower AC voltage 1st.
Was looking for something simple to wire into the circuit to drop the AC. I have a multimeter, can measure output before apply to loco.
If I need to go to RS etc, what should I look for that won't bankrupt me??
You can put a series of diodes in. Then bridge across the diode range. For example, if you bridge across 1 diode pair, you would have about 1.7Volts AC. If you bridge across 2 diode pairs in series, you would have about 3.4 V AC. However you will have to put a limiting resistor in series with the circuit, or your diodes and or power pack will go Big Badda BOOM!
You can also go to jameco and look up IC voltage regulators. (These are mega cheap)
http://www.jameco.com/webapp/wcs/stores/servlet/ParametricSearchResultsView?langId=-1&storeId=10001&catalogId=10001&jameco_page=46&drill_parents=category_root%24%2410%24%241015%24%241015%24%241015%24%241015%24%241015%24%241015&drill_children=10%24%241015%24%24101560%24%24101561%24%24101565%24%24101566%24%24101570%24%24101571&drill_displays=ICs%20%26%20Semiconductors%20%2F%20Analog%2FLinear%20%2F%20V-Regs%24%24ICs%20%26%20Semiconductors%20%2F%20Analog%2FLinear%20%2F%20V-Regs%20(SMD)%24%24ICs%20%26%20Semiconductors%20%2F%20Analog%2FLinear%20%2F%20V-Regs%2C%20LDO%24%24ICs%20%26%20Semiconductors%20%2F%20Analog%2FLinear%20%2F%20V-Regs%2C%20LDO%20(SMD)%24%24ICs%20%26%20Semiconductors%20%2F%20Analog%2FLinear%20%2F%20V-Regs%2C%20Switching%24%24ICs%20%26%20Semiconductors%20%2F%20Analog%2FLinear%20%2F%20V-Regs%2C%20Switching%20(SMD)
If all depends on how many amps you need.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
TankedEngine I have an HO Marklin Loco that I want to hook up on alligator clips to get the motor ticking over. I don't run Marklin AC track. I have been told I need about 5v to 8v AC to start the motor. The closest I can get with current equipement is the 17v AC off the back of the HO DC power pack & prefer try a lower AC voltage 1st. Was looking for something simple to wire into the circuit to drop the AC. I have a multimeter, can measure output before apply to loco. If I need to go to RS etc, what should I look for that won't bankrupt me?? Tanked
I have good news and good news.
Your Marklin locomotive doesn't care whether it sees DC or AC to make the motor turn. In fact, some Marklin locomotives have DC-only can motors with rectifiers and other electronics in front of them. Most modern 3 rail O has switched to can motors with rectifiers and electronics in front, too. Now, reversing and other features provided by the electronics won't work on DC, but the motor will certainly turn. So just hook up your 0-12 volt DC output to your alligator clips and go for it.
The other very good alternative is to beg or borrow a Lionel, American Flyer, or other 3 rail O transformer. All these produce variable AC voltages in the correct range. Again, Marklin's reversing pulse is unique so these transformers can't reverse your locomotive, but they can certainly provide power to the motor and/or track. The only gotcha to watch for is that some of the older Lionel transformers had a minimum 6 volt output, with the variable range being 6-16 volts. Usually these older Lionel transformers had a separate set of taps to bypass the 6 volt winding and get a variable 0-11 volt output.
Bottom line rule: AC universal motors run on AC or DC. DC permanent magnet motors are DC only.
Hope this helps