Hi all, Been working on an led light project, trying to get the most useful room light from 1 watt or less.
I made led light fixtures for the project also, using poster board with a highly reflective silver on one side, from hobby lobby.
Also made a large coil/core for the oscillator, used 15 ferrite toroids stacked and glued together, then wound one layer of 30awg. magnet wire and on top of that, a layer of 24 awg. magnet wire.
And used similar oscillator circuit from the rene/aum experiments, will post actual circuit drawing soon.
Setup uses 960 milliwatts and provides fairly bright light in all areas needed, using six 40 watt equivalent modified led bulbs in parallel with light fixtures at the moment.
The light fixtures help reduce light spilling off into walls and angled ceiling, where light is not needed, as these walls are brown and does not help.
Using boost converter as input, 11.56 volts at 83 milliamps.
Using four 1n4004 diodes as bridge rectifier off the 30 awg. secondary coil to power the led bulbs.
The ferrite core itself, weighs 15.3 ounces.
Comments welcome.
peace love light :)
thanks sky. is any schematic of your circuit ?
thanks
Hi erfandl, yes, just finished it.
peace love light
Quote from: SkyWatcher123 on July 01, 2018, 10:27:17 PM
Hi erfandl, yes, just finished it.
peace love light
thanks sky. is 2 wire wrapped clockwise or counterclockwise ? ( first layer clockwise and second layer counterclockwise ? ) and whats the toroid size ?
thanks
Hi SkyWatcher,
It is a good idea to use the light fixtures to increase brightness for the needed areas. You may have thought of testing the actual position of a bulb within the fixture, I mean attaining a virtual focus point position when the most light is reflected back from the silver coatings and directed to the facing front of such lamp.
Regarding your circuit, we have discussed its lossy components in your other threads and how to reduce losses, no need to repeat them here, you know them. 8) The difference maybe that the operational frequency of this oscillator is lower than the earlier ones due to the higher number of turns and more ferrite core mass (i.e. primary coil inductance is higher).
Gyula
Hi erfandl, thanks for the reply.
Both coil layers are wound in same direction, though that would not matter anyway, as they are separate coil layers.
I bought the ferrite toroids here: https://www.sciplus.com/ferrite-toroids-55644-p (https://www.sciplus.com/ferrite-toroids-55644-p)
Hi gyulasun, thanks for the reply.
The light fixtures focus seems to be well enough and is making a smaller area brighter, as you point out.
The circuit is oscillating at a fairly high frequency, as heard using my headphones close to the coil, so faster diodes for the bridge would probably help.
This is a project, so I plan to tweak and make inprovements where possible, keeping with the 1 watt or less input idea.
peace love light :)
How many tuns primary and secondary
Quote from: SkyWatcher123 on July 02, 2018, 12:43:16 PM
Hi erfandl, thanks for the reply.
Both coil layers are wound in same direction, though that would not matter anyway, as they are separate coil layers.
I bought the ferrite toroids here: https://www.sciplus.com/ferrite-toroids-55644-p (https://www.sciplus.com/ferrite-toroids-55644-p)
Hi gyulasun, thanks for the reply.
The light fixtures focus seems to be well enough and is making a smaller area brighter, as you point out.
The circuit is oscillating at a fairly high frequency, as heard using my headphones close to the coil, so faster diodes for the bridge would probably help.
This is a project, so I plan to tweak and make inprovements where possible, keeping with the 1 watt or less input idea.
peace love light :)
thanks for answer. is layer 1 is under the tape ? or like the below picture ?
thanks
Hi ed, i did not count the turns.
Hi erfandl, the circuit drawing says it clearly, first layer is 1 full layer of 30 awg. magnet wire, which is on top of the ferrite core, with thick paper covering the core, then the coil.
The second layer is 1 full layer of 24 awg. magnet wire.
The tape or coil mess you see in the picture, is because the 30 awg. snapped on me while winding the first layer and i soldered and taped it together, so it is sticking out a bit in the middle area.
peace love light :)
Edit: hmm, interesting, i placed another diode in parallel with each of the diodes in the homemade full wave bridge, specifically, 1n4002's, as i have no more 1n4004's on hand.
Surpisingly, the light output has increased noticeably, while the input dropped slightly.
Quote from: SkyWatcher123 on July 02, 2018, 10:52:40 PM
Hi ed, i did not count the turns.
Hi erfandl, the circuit drawing says it clearly, first layer is 1 full layer of 30 awg. magnet wire, which is on top of the ferrite core, with thick paper covering the core, then the coil.
The second layer is 1 full layer of 24 awg. magnet wire.
The tape or coil mess you see in the picture, is because the 30 awg. snapped on me while winding the first layer and i soldered and taped it together, so it is sticking out a bit in the middle area.
peace love light :)
Edit: hmm, interesting, i placed another diode in parallel with each of the diodes in the homemade full wave bridge, specifically, 1n4002's, as i have no more 1n4004's on hand.
Surpisingly, the light output has increased noticeably, while the input dropped slightly.
thanks. I understood. sorry for noob questions :P
Hi all, I made some tweaks to the project.
I picked up a diode assortment at frys, happened to have 50 1n4007's in the set also.
So I made a new full wave bridge with 4 - 1n4007's in parallel per branch, so 16 total diodes for the full wave bridge.
Again, the brightness noticeably increased and the input dropped 30 milliwatts this time, with previous bridge, it only dropped a few millwatts.
Here is a short video that gives an honest representation of the lighting level, input is 932 milliwatts now.
https://youtu.be/Lk00vIxcxLs (https://youtu.be/Lk00vIxcxLs)
And here is the new full wave bridge.
Comments or questions welcome.
peace love light :)
Edit: Actually, I notice after watching the uploaded video, it degraded the quality a little and reduced the lighting that is seen with the eyes.
Hi SkyWatcher,
Nice results and good job with paralleling the diodes. I think that only germanium type diodes can beat your diode assembly if you are thinking of further improvement for the diodes. Let me show you this link: https://picclick.ca/USSR-Rectifier-Germanium-Diode-D7J-D7Z-%D0%947%D0%96-If-300ma-382453550737.html where a Russian type Germanium diode, D7Z (400V, 300mA) is compared (by a diode checker DMM) to an also Russian military type diode (200V, 10A) probably Schottky type (but said to be Silicon but for silicon material the forward voltage is around minimum 500-600 mV or higher).
The meters show forward voltage drops, and the forward current the meter drives through them is usually 1mA but for a single 1N4007 such 1mA may display anything between say 550-670: this display means the forward voltage drop in mV across the diode and not the resistance of the diode as stated in the picture.
IF you have a digital multimeter that also has a Diode symbol in its Ohms measuring range (or next to it), you can easily check this, also for any of the 4 parallel diodes in the bridge.
So the good thing for the D7Z type is that it has 130 mV forward voltage drop at probably 1 mA and it is sure that say at 100-150 mA forward current the voltage drop must be around 200-250 mV maximum. And you can easily confront this with your 4 diodes presently in parallel: what your DMM shows for them?
Then you can decide whether probably the higher than 200% reducement in overall diode loss would be worth the cost for the Ge diodes. Here I assume your parallel 4 diodes have roughly 400-450 mV forward voltage drop at say 50-100 mA forward current.
If you do not have a DMM with Diode test feature, you can drive a given DC current in forward direction via any of the 4 paralleled diodes from the bridge and measure DC voltage across them with your DMM.
Say you have a DC source of a 12.7V battery (or any other type), then you calculate a resistor value and connect that resistor in series with the diode (or with the 4 parallel diodes of course) and then you connect this series R and Diode assembly across the battery. For a 50 mA forward current the R series resistor would be 12 V / 0.05 A = 240 Ohm. For 100 mA forward current use a 120 Ohm resistor (these should be at least 1-2 W rated resistors or measure quicly not to let the R heat up too much).
Here is another ebay offer with free shipping for 10 pieces of D7Z Ge diodes:
https://www.ebay.com/itm/202340101831
or here is an offer for 4 pieces (but shipping is not free): https://www.ebay.ca/itm/253341986352
The technical specifications for the 200V 10A diode is here at the bottom of this link if you need them:
https://www.ebay.com/itm/323306203220
The 3.33 kOhm emitter resistor possibly dissipates 8-9 mW DC power (my rough estimation) if you consider that to reduce (but it would be hard... by selecting the transistors I suppose).
Gyula
Hi gyulasun, thanks for the helpful information.
I checked some of the diodes i have with my Centech 61593 meter, it does have diode test setting.
Here is some forward voltage drop data of diodes i have.
1n4007 = 535 mV
1n5408 = 474 mV
1n4148 = 565 mV
1n5822 = 117 mV
6A6 = 453 mV
---------------------------
4-1n4007 in parallel = 465 mV
8-1n4148 in parallel = 455 mV
The 1n4007's in parallel seem the best so far, for this coil/core setup and the higher voltage is good safety margin, as without a load off bridge to bring down the voltage, the 1n4148's can die.
Still going to try and optimize the project and have some comparison tests to make and see how the light output compares to off the shelf led bulbs.
peace love light :)