Jump to content

Why C9 retro LED's don't need rectifiers?


Recommended Posts

Following this Forum for a few years and trying to educate myself about the various types of LED lighting, Full wave vs half wave. I'm not sure but the full wave LED's have rectifiers which convert to line voltage to DC. (I think) Why do the retro C9 and C7 bulbs just use the existing AC voltage to operate. No need for rectifiers which seem to be the main cause of failures. I have purchased from Paul and Travis in the past few years and have had very few light strings ( just a couple-really not worth mentioning) fail.

Jimmy

Link to post
Share on other sites

Better yet why dont half waves have any rectifiers on them?? do half waves run on AC and fulls run on DC?? Why dont they make most full waves have a single rectifier box like commercial LEDs have and then no more problems with blobs?? who put the bop in the bop da bop da bop?? : )

Jim

Link to post
Share on other sites

B the holiday creations half wave (such as sold last year at hobby lobby) have no blobs and the same tiny stackable plug ends as the full waves have. Boy did hobby lobbby screw up getting rid of these!! they work, look, and behave great!!

Link to post
Share on other sites

I use plenty of HW LEDs as well as FW LEDs. Unless they are on for an extended period of time, you can not see a difference with all of the lights blinking. If I had a static display, it might be easier to spot. I will say though, if you are happy with the Holiday Creations HW lights, the FW lights will blow you away. They are magnificent.

I didn't know Hobby Lobby carried H/C LEDs; then again, we do not have one close by. Hobby Lobby is not listed on the Holiday Creations website as a retailer either.

Link to post
Share on other sites

B hobby lobby stores carry the GE brand this year.. last year they were actually packaged for westinghouse but say holiday creations on the back of the box. I have both HC full wave from travis and HC half wave from hobby lobby. I mix the blue outline on the front of my house with C6 fulls and halfs and NOBODY has been able to pick the halfs out of the mix!!

Link to post
Share on other sites

Rectifiers do NOT make DC current, they merely allow the LED's to turn off 120 times a second, instead of 60 (with half of that time actually OFF). Your incandescents turn off and on 120 times a second, they just glow from heating and don't actually make it to 'off' for very long.

So if we add a rectifier to make a full wave LED string, each LED will be on twice as often, and thus appear much brighter.

Link to post
Share on other sites

Correct, although unless there is enough resistance in the line, or some added resistance, the LED's will burn up quite quickly with DC current.

I'd be very curious about the guy who cut the 'blobs' off his strings and connected them up to a car battery. First off, there is not enough voltage to light most LED strands (since each LED will want to drop about 2 volts). Secondly, they're sure not going to run very long before the go poof!

Well, I take that part back. Provided you don't have too much voltage, the string 'could' run properly, but a 12V car battery isn't going to run much more than 6 to 10 LED's in a series-wired string.

Edited by chuckd
Link to post
Share on other sites

Rectifiers do NOT make DC current

According to what I learned back in school, the purpose of a rectifer circuit (in general) is to convert AC to DC. There may be capacitors added in a power supply circuit to make that rectified DC more pure and less "pulsating". But there are also half-wave rectifers and full-wave rectifers...

This website provides more info:

http://www.play-hookey.com/ac_theory/ps_rectifiers.html

Link to post
Share on other sites

There's some argument in the industry as to whether or not current that is constantly changing from 0 to some value should be called DC, or 'pulsed'. In this fashion, DC is used to mean 'not alternating'. One of my professors was a stickler on this point, as he thought it should mean a continuous uni-directional source of current.

I've always adhered to the pulsed current definition myself. DC was always reserved for continuous (but admittedly slightly pulsing) current.

Problem is, people equate DC to a battery, and rectified AC most definitely does not behave like a battery.

It's really semantics, though. I think we're both on the same page.

Link to post
Share on other sites

Well I suppose I am from the old school. DC means current that comes in on one wire and leaves on the other (one way). Where as A.C. means that the current goes both ways on one wire. And the other wire the current goes both ways, but is 180 degrees opposite than the first wire.

The pulsing of the voltage / current was a non-issue. Just the fact of the direction of the current flow. Thus I had a little problem with your statement that Diodes do not create D.C.

Link to post
Share on other sites

They definitely create one way current, so I can accept that. But if you bought a DC power supply that only produced half or full wave rectified AC, you'd be pretty upset. That's the basis for not referring to rectified AC as DC. I do have textbooks that call it DC, though.

Link to post
Share on other sites

I've always understood it as AC=voltage that swings around 0 volts, goes positive-negative. They key is that it switches polarity. That's AC.

Even noisy DC never switches polarity.

That's why most people who understand electronics will say even halve wave rectification is technically DC. It never crosses 0 volts or changes polarity. We also understand that the cleanest form of DC is from a battery.

Link to post
Share on other sites
Guest csx5861

Rectifiers do NOT make DC current.

No they DO NOT MAKE DC current (only a battery in a sense makes DC current), BUT THEY DO CONVERT ~AC~ CURRENT to DC CURRENT! And that is a FACT!

I build FULL WAVE BRIDGE RECTIFIERS for my projects all the time, using 4 diodes or I may buy a pre-constructed one from Radio Shack, THEY DO, IN FACT, CONVERT ~AC~ to DC voltage, no matter what ~AC~ voltage you feed in, you will get that EXACT voltage out in DC form! 9V~AC in = 9 VDC out, 24V~AC in = 24VDC out, 120V~AC in = 120VDC out, etc.

I use old ~AC~ output adapters that I have lying around to supply voltages for many of my "home brews" and use regulators to drop DC output from an ~AC~ adapter down to whatever voltage I may need. I have a lot of old ~AC~ output adapters, ranging from 6VAC to 24VAC, so I use a 7805, 7809, or 7812 voltage regulator off the DC side of the FW Bridge Rectifier to drop this ~AC~ voltage to 5vdc, 9vdc or 12vdc depending on my requirments.

Edited by csx5861
Link to post
Share on other sites

So your claim is...... use a bridge rectifier ONLY on US household AC (no capacitors), whip out the DMM and turn it to DC volts, and you'll measure 120? Try it and see what you get.

I'll definitely agree that the RMS voltage is still 120, and I'll agree (if you look at my earlier post), that the current only goes one direction, which I'm now begrudgingly calling DC.

Edited by chuckd
Link to post
Share on other sites
Guest csx5861

So your claim is...... use a bridge rectifier ONLY on US household AC (no capacitors), whip out the DMM and turn it to DC volts, and you'll measure 120? Try it and see what you get.

I'll definitely agree that the RMS voltage is still 120, and I'll agree (if you look at my earlier post), that the current only goes one direction, which I'm now begrudgingly calling DC.

My DMM reads 110v-120v DC on the output of a FWDB when 110v-120v~ AC is input through the ~AC~ inputs of the FWDB. I have never gotten anything less, but I try NOT to use 110v-120v directly though a FWDB, but use a step-down transformer between the FWDB and Transformer output side.

Actually no, sometimes I use a diode bridge on DC "battery operated" circuits as well, no capacitor required as it is only being used as a wrong way battery protector, this way it doesn't make any difference what way the battery (batteries) are inserted in the device, if they are put in the wrong way, the FWDB still maintains the correct polarity to the device under power. To do this you feed the DC source through the FWDB's ~AC~ inputs and as long as the FWDB's outputs are - to - of the device and + to + of the device, no matter which way the battery gets inserted, the device will always see the correct polarity, preventing damage from installing the battery (batteries) in backwards. I tend to add a FWDB to anything I use or own that requires battery power that utilizes L.E.D.'s or DC motors.

I sometimes will use a capacitor, it depends on what I am powering. Motors I use a capcitor to help the start up of the motor as well as help keep it quiet, if powering something like an FM Transmitter, definitely gets a cap to help filter the AC to prevent hum, but if I'm powering lights (incandescent) or even L.E.D.'s I have seen no reason to use a capacitor on the circuit for those type projects. Just a voltage regulator and possibly a resistor to drop the voltage down. I usually do not use 120V direct, if I do use 120V~ AC, I'll use a step-down transformer to drop the voltage, then a FWDB with a Voltage Regulator to drop the voltage to whatever DC voltage I need to power the item. Again, depending on what it's powering will determine if a capacitor is required or not.

Clay

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...