TE - Quick disconnect power connectors for heavy gauge cables

Hi all,

Just one final thought: is it permissible to use a Triac as a variable resistor? I mean being able to control the Vout infinitely from 0V to

240VAC simply by adjusting the gate bias to the device? ISTR with MOSFETs this doesn't work, since they like to be either ON or OFF and get all hot and bothered with anything in between those two extremes. But.. triacs? Can a triac handle that kind of more linear role?

thanks!

Nope. A TRIAC is a 5-layer device which exhibits hysteresis when the "gate" reaches a critical threshold, pretty much like an SCR.

A MOSFET can be operated as a controllable resistor over a small voltage drop range, somewhere between +/-0.5V and +/-1V.

You _can_ control the phase of the gating of a TRIAC and produce an "effective" AC voltage... this is how light dimmers work.

What are you trying to do now ?>:-} ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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             I'm looking for work... see my website.

Andersons are hard to beat IMO:

I'm just a teeny bit concerned about running this 60V bell at 240V, that's all. I know it's put up with it admirably so far during extended tests, but from a design PoV it doesn't seem right (obviously!). I have a selection of old-style multi-tapped mains dropping resistors here. Since the bell only draws 60mA, this becomes feasible to use one. Unfortunately it would mean expecting a 20W MDR to dissipate 56W (it's only 1k between furthest tappings). However, it would only be on for 2 seconds every 90 seconds, so there's time to cool down. However (again!) the ceramic core of the MDR does a marvellous job of retaining heat, so the outcome is that over time the MDR just gets slowly hotter and hotter and hotter. I haven't run it long enough to see if it ever tops out at some tolerable temperature, but a 15m test suggests it won't! :(

Try phase controlled TRIAC ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 

             I'm looking for work... see my website.

You mean phase-controlling the Triac, presumably? I can't see how that would help. Power factor correction is not an issue in this case (it's just a one-off gadget for my own use).

reduced.

You problem posing is almost at "XY Problem" level ;-) Is your bell actually a DC device? ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 

             I'm looking for work... see my website.

[...]

Gosh, Jim, we're almost having a real-time conversation here. We should be discussing US politics. ;-)

That would require firing it by means of a synchronised pulse train, surely. An extra level of complication!

Not sure what an XY problem is outside of oscilloscope territory. The bell is *definitely* AC; it contains no switchgear whatsoever.

No synchronization... just a delay from zero-crossing.

"XY Problem" ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 

             I'm looking for work... see my website.

Ah, I see. But still requiring a pulse train, clearly.

Oh, this looks like something profound the likes of Robert Pirsig would formulate. I may be away some time......

No. Just an RC and a DIAC typically, though there's many ways to skin that cat. Look up phase controlling a TRIAC for examples.

;-) ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 

             I'm looking for work... see my website.

Jim,

The bell is obviously an old telephone ringer, with an U-shaped electromagnet and a magnetic anchor, so a kind of synchronous motor intended for 20 Hz and 60 V AC. There is a bell striker attached to the anchor and usually two bells to strike.

--

-TV

That's not what Julian said. ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 

             I'm looking for work... see my website.

I think Tauno has embellished a bit somewhat. ;-)

What I actually said was: "It's a light load, btw (a 4k ohm exterior telephone bell which requires 240VAC) so doesn't need much current."

Of course I now know it's 60V and not 240V. However, I have also established that the frequency it works most effectively and efficiently at is 35Hz. The internal electromagnet is *not* U-shaped. It's a straight bar solenoid 3" long with a rocker mounted against the middle so that with every pole-shift, the ends of the rocker can pivot towards alternate ends of the solenoid as the polarity changes with the current. There's a hammer attached at right angles to rocker so as it see-saws (teeter- totters) this hammer strikes the two bells alternately. I've no idea where this 35Hz comes from. I'd have thought the phone company would have used 50 or 60Hz to make it compatible with the power grid and therefore simpler and cheaper to manufacture. Anyway, to get a decent sound level out of it at 50Hz (as is the case here) requires at least 175VAC., and at 240VAC, it sounds absolutely tip-top!

I don't recall that. Can you give us the relevant message ID?

[snip]

The original telephone bells were actuated by a hand-cranked "ringer" that put out roughly 100 VAC at 25 Hz. Since it is an inductor, the reactance is proportional to frequency, and the operational voltage for the same current is also proportional. So the voltage at 50 Hz would be 200, and at 60 Hz it would be 240.

The "clapper" will vibrate at the supplied frequency, so the tone will be higher at 60 Hz. Also, the amplitude of swing may be reduced at the higher frequency because of the inertia of the clapper versus the magnetic force due to the current.

No TRIAC or voltage reduction should be needed! :)

Paul

IF you want it to ring continuously... something has to switch it on and off >:-} ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 

             I'm looking for work... see my website.

If you're not replying, don't hit reply. or are quick disconnects somehow relevant?

Yeah, well about 10 to 238V anyway and so long as you don't need a sine wave. and it's not a DC bias adjustemnt

Anyway for your bell driver you want to skip two out od three AC lobes, that'll get you an approximation of about 16.7 Hz at about 80V

There's probably a way to use a triac and a couple of of SCRs to do that. But figuring it out seems like a good way to destroy parts.

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Not a big complication, however; one resistor, one capacitor, and a trigger device called a 'diac' (and maybe a gate current liimit resistor) will do i t, using two polarities of triac gate drive. Don't experiment without a current limit, however, this CAN rectify your AC which would be bad.