Daddy Dee Posted April 1, 2005 Share Posted April 1, 2005 O.K. transformers... On my amps, I find power transformers, output transformers and chokes... I think I understand that power transformers would provide power to the tubes and that output transformers are the last stop for the signal on the way out to the speakers. That is obviously quite a limited understanding. What purpose of the choke? What's the difference between a choke and a transformer? Any enlightenment is sincerely appreciated. Quote Link to comment Share on other sites More sharing options...
lynnm Posted April 1, 2005 Share Posted April 1, 2005 Transformers modify the AC voltage applied to them by either increasing or decreasing the output voltage. Power transformers may have several output taps which means that an input voltage of 110 volts AC to a transformer can be output as say 6.3 volts for tube filaments and 350 volts for the plate supply and so on. Chokes are not intended for modifying the voltage applied to them but have the useful characteristic of passing AC but not DC. They are typically used in power supply circuits to bleed off any residual AC to ground thus further cleaning up the DC fed to the rest of the circuit. Hope this is helpful. Quote Link to comment Share on other sites More sharing options...
Mark Hardy Posted April 1, 2005 Share Posted April 1, 2005 A choke is an inductor; a coil of wire. If you pass DC through it, it becomes an electromagnet :-) When you pass AC through it, it acts as a filter, attenuating higher frequencies but passing low ones. The characteristics of a choke/coil/inductor/solenoid will depend upon the DC resistance and the inductance (measured in units of Henries, H). The parameters are determined by the number of turns of wire, the gauge of wire, and the magnetic permeability of whatever forms the core of the choke (air vs. ferrite, for example). Chokes are used to filter AC line frequency in power supplies, as crossover components in speakers and as filters in RF circuits (also as components in tuned circuits, but I ain't going there). Does this help? Quote Link to comment Share on other sites More sharing options...
3dzapper Posted April 1, 2005 Share Posted April 1, 2005 Your choke performs two functions, first the choke smooths the power supply ripple through it's resistance and inductance. These factors form an LC time constant which slows the rate of rise and fall in the rate of voltage rise in the ripple left over from rectification and input capacitor. Second the choke stores energy in it's magnetic field. When there are high energy demands the field within the choke collapses somewhat inducing voltage in the windings to provide some of the extra power needed for transients. In this function the choke is acting like the coil in your car except there is only one winding. Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted April 1, 2005 Author Share Posted April 1, 2005 Gentlemen: Thank you. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted April 1, 2005 Share Posted April 1, 2005 ---------------- On 4/1/2005 12:20:13 PM 3dzapper wrote: Your choke performs two functions, first the choke smooths the power supply ripple through it's resistance and inductance. These factors form an LC time constant which slows the rate of rise and fall in the rate of voltage rise in the ripple left over from rectification and input capacitor. ***I've played with the Duncan PS program and seen that. What I have noticed is the choke(depending on value) kicks up a big spike on the load line, then you have to beat it back down with a cap(using capacitance). I've tried straight LC, didn't look too good on the program. LCLC looked good, with a small second choke. I have to sit down and figure up the reflected primary impendance on the secondary, to input the proper secondary impedance. Second the choke stores energy in it's magnetic field. When there are high energy demands the field within the choke collapses somewhat inducing voltage in the windings to provide some of the extra power needed for transients. In this function the choke is acting like the coil in your car except there is only one winding. ***Interesting.... I need a pair of 3 henrie chokes at about 250 milliamps, 270 would be better..... ---------------- Quote Link to comment Share on other sites More sharing options...
D-MAN Posted April 1, 2005 Share Posted April 1, 2005 A choke is just another name for a coil, usually the term choke is indicative of being a coil wound on a transformer frame, but can be used to indicate its use inside of a circuit, instead. So transformers can be chokes, too, depending on the use. DM Quote Link to comment Share on other sites More sharing options...
khorny Posted April 1, 2005 Share Posted April 1, 2005 'I need a pair of 3 henrie chokes at about 250 milliamps, 270 would be better.....' http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=3280&item=5762826686&rd=1&ssPageName=WDVW Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.