Moderators: Dave Moll, Andrew Davie, Steve Anderson
Andrew Davie wrote:Have to admit I really love the crazy stuff you make and how you re-use stuff.
It would make a GREAT YouTube series just watching you tinker and see the results you get.
Steve Anderson wrote:The larger distributors will have low-ohm resistors, generally power versions and wire-wound of 2W or more (up to 100W). In that circuit they're for current equalising between the output pairs as well as thermal stability. It must be a very old circuit as most would use MOSFETs today which are generally more rugged in this sort of application. They also don't suffer from 'thermal run-away'
The 0.33 Ohm resistors can be made of 3x1-ohm in parallel. Below 1-Ohm they often noted by the value being R33 for a 0.33 Ohm version, instead of 100R for a 100 Ohm version (or simply 100, no decimal point, no multiplier prefix/suffix), in a similar manner for a 4.7 Ohm, 4R7, the 'R' taking the place of the decimal point which can often get lost when printing...same idea as 'k', 4k7, not 4.7k, or 1M5 instead of 1.5M. You'll notice I do that in all my circuits...
Applies too for capacitors and inductors, 4n7 not 4.7n, 6u8 not 6.8u(Henry).
The 2N3055s are only rated to 60V, the transformer 75V RMS will produce over 100V after the bridge rectifier, even without allowing for transformer regulation. So I suggest you scrap that circuit, it'll only cause grief!
It really annoys me (I can think of a better expression) to see so much utter rubbish published...
Steve A.
Steve Anderson wrote:Start with your requirements...how much voltage, how much current, is the load resistive, inductive or capacitive? Or a combination of all three...loudspeakers are a good example, especially with cross-over networks within. In this case probably mostly capacitive which at higher frequencies will require perhaps quite a bit of current...though not excessive.
Stability is also a factor, the load capacitance can affect feedback networks to varying degrees. Driving high-capacitance load is not easy, but can be done.
Steve A.
smeezekitty wrote:What impedance is the cartridge though? If you're using an amplifier with an 8 ohm speaker output for 1kOhm load for example, you won't get good results at all. If the amplifier impedance matches the cartridge, I bet you'll need far less than 100 watts - because if there is a mismatch, you're not actually delivering ~70W into it. Probably less than 10.
Return to Construction Diaries
Users browsing this forum: No registered users and 3 guests