Is it ok to use a vintage foreign electricity converter?

We have one of those too. I've taken the plug converter out of it and put it with our other plug converters. The rest of the kit is pretty useless unless you just need a plug converter. The two round prong converter plug will work where you are going.

Lets be sure of our terms. There is a BIG difference between a voltage converter and a plug adapter. Which is it??? There no such thing as a plug converter. If it is strictly a plug adapter - changing one set of prongs to another. Then you are fine but it is actually changing 220/240 volts to 120 volts, then I might have some concerns depending on anticipated usage. So which is it?

Are you bringing any electronic devices that don't already work with either 110 or 220 voltage? Check the very fine print on each one. See also http://www.ricksteves.com/travel-tips/phones-tech/electric-adapters-converters.

I should have used the term "plug adapter" instead to "plug converter". The former converts the configuration from North Americal plugs to European plugs, thus allowing your 110/220 items to be used in Europe as weill as in North Americal. Clear as a bell!

http://voltage-converter-transformers.blogspot.com/2011/08/differences-between-voltage-converter.html

This highlights the first difference between a Voltage Converter and a voltage transformer. For a layman, these two types of devices have the same meaning. No doubts that converters and transformers perform similar function, but their approach and application differ. While converters are used for electrical appliances that are usually used for less than an hour every time, transformers are used for electronic devices that may have hours of usage.
You must know that transformers can be used even for electrical devices, but a voltage converter can’t be used for electronic devices. Another difference between the two sets of devices is that a Step Up and Down Voltage Transformers is always bigger and heavier than a converter. This is because of the more complex function that the former has to perform. If you know that AC power travel in the form of a sine wave, you must know that a converter simply needs to chop it off to adjust the voltage. On the other hand, a transformer needs to adjust the length of the wave.

and you won't be visiting Czechoslovakia unless you are going back in time , maybe your converter can do that for you. You will be visiting the Czech republic and or Slovakia.
Please by a new one, or at least have it properly tested before you go.

Unless you are going to the UK, these will work just fine: http://www.amazon.com/American-European-Germany-Adapters-Certified/dp/B00EOI2N2M/ref=sr_1_2?ie=UTF8&qid=1437445237&sr=8-2&keywords=schuko+plug+adapter They are properly grounded, fit the socket properly as opposed to the cheap square ones, and they will last a life time. I did give one of the cheap ones I had kicking around to a friend who used it and got shocked when the plastic housing fell off while he was unplugging it. So, get new stuff and good stuff. Its too cheap not to do it correctly.

As for the voltage reducing transformer..................throw it away. Its heavy, bulky and serves no purpose in the 21st Century.

Wow, thanks for all the response! Sorry I'm so late getting back to everyone. Monte, I called it a Franzus Foreign Electricity Converter because that's what it says on one of the bigger plugs. That same plug also says "converts 220-240V-AC to 110/120 V-AC. Think I'll just get the new one that James suggested. Thanks again!

Yes, that's right. Its the bigger square one in the set. Don't use it, but you can still use the little two and three prong adapters.

Remember, what I suggest just allows your thing to plug into their thing. Its a plug adapter. The voltage still has to be compatible. Almost All, if not ALL power transformers for phones, laptops, etc are dual voltage. You only need the plug adapter. Curling Irons and the like are a different issue all together. Still, you don't buy a voltage converter, you buy a travel or dual voltage version of the curling iron or what ever it is. Or maybe yours is that way. It will say so someplace on it if true.

Here is a list of all foreign countries and the types of plugs that can be used. Note, the type C plug (2 pin "Europlug") can be used in all of them. However, it is limited by codes to applications drawing no more than 2½ amps (575 Watts at 230¹ Volts), well less than most hair dryers.

For wattage greater than 575W or if your appliance has a US grounding plug (third, round pin), you should use the plug linked to by James (type E or type F). I think James' plug fits both types E and F receptacles. It's a little hard to tell. Type E plug has a round hole to accept the protruding grounded pin for a French "Schuko" receptacle used in France, Czech Republic, and Slovakia. I think I can just barely see the edges of the hole behind the LH pin on the picture of the receptacle, so it would work in type E receptacles.

The picture of James' plug seems to show both slots the same length (I hope they are, but probably not). If so, it would not accept an American polarized plug (one blade wider that the other, which is the type of plug used on a lot of curling irons, etc. A polarized plug is required by UL because it provides safety when used in a polarized American receptacle, but European receptacles, with rare exception, are not polarized. Appliances with a polarized plug are not safe for use in Europe!

¹ It used to be that the UK used 240V and the continent used 220V. 230V is now the standard for the entire EU.

tisntom, do you need a converter? What exactly are you taking? If it's newer electronics (cell phones, cameras, tablets, some hair appliances) you won't need a converter. You'll need adapters. HUGE difference!