total novice would like to know if it is possible to..

[stevehawkes]

Hi,

I am a chef and a total novice when it comes to electronics.

I have a Velleman strobe kit.
When I bought it the back of the pack said it could adjust the flashing time.
I took that to mean that I could adjust the length of the flash, but it meant the time between flashes.

I want to modify the kit to allow me to be adle to increase the length of flash but retain the facility the kit already has.

Please can somebody advise if this is possible

I attach a PDF of the oinstructions that came with the kit

please please shout out if you can help as I know nothing much about electronics..................

regards and thanks

Stephen

 

[mramos1]

I do not think they are designed to do that. What are you tring to use it for?

 

[stevez]

The duration of the flash is limited by the circuitry and by the design of the flashtube itself. A flashtube that is producing light for a long period of time is really a high intensity discharge light. Usually an HID power supply provided a striking voltage to start the light and a much lower voltage to sustain it. Chances are good that you'd have to start fresh with the power supply and check with the flashtube manufacturer to see how long you might leave the light "on" - if the construction of the tube allows.

 

[stevehawkes]

The circuit has two LED that you can control the speed of flash.
(the time between flashes can be increased / decreased)

I am trying to make the two LED's iluminate for longer.
i.e. make the flash longer / increase the legth of time that they are lit

I know next to nothing about electronics and it may not be possible to modify the kit I have built. I just thought I'd shout out and see if somebody knew.

hope some one can help me

regards

Stephen

 

[stevehawkes]

please, please keep your answers simple

I don;t understand ANY jargon ect.

I am a chef by trade and have no experience of any electronics anything.

Like " flash tube " I simply have no idea what that is


thanks to all of you for your patience with me

regards

Stephen

 

[Roff]

There is no flash tube, guys. The LEDs are the flash. You can make them stay on longer by increasing the value of R2. As designed, the flash time is about 68 milliseconds. The width is linearly proportional to the value of R2.

 

[stevez]

Was thinking of stobe kit with flash tube - can't get to download, not sure why.

 

[audioguru]

The LEDs can be kissed good-bye if their "on" time is increased. If they survive operating at a whopping 227mA I guess you can kiss the little 9V battery good-bye too.

The LEDs look ordinary, not like high-current Luxeons. If they are 2V red ones, then the 22 ohm current-limiting resistor also might melt with 5 V across it.

My LED blinkers operate my ultra-bright "ordinary" LEDs at 90mA with an on time of 50ms, and they are blinding. Their pulsed absolute max is 100mA and their continuous max is 30mA so I wouldn't dare to increase their on time. :lol:

 

[Roff]

The schematic page says they are white LEDs. I'm guessing they are pulsed at somewhere between 50 and 100ma, depending on fwd voltage. I agree that they might die if the pulse width is increased significantly. It would be good to see if you can locate replacements before you try this.

 

[Roff]

A potential problem with this design is repeated T2 base-emitter breakdown. The max spec is -6V, while the base will try to go to about -8.2V. This will result in repeated short reverse base-emitter current pulses in the hundreds of milliamps range. Conventional wisdom is that this results in beta degradation which worsens over time. One solution is a 1N4148, cathode to T2 base, and a 4.7V zener (e.g., 1N750), anode to 1N4148 anode, cathode to GND.

 

[audioguru]

These old circuits that were designed for germanium transistors that didn't breakdown keep appearing with silicon transistors.

 

[mstechca]

After I took a visit at Talking electronics Interactive at http://www.talkingelectronics.com, I found that they have many useful circuits, one of them which could suit your requirements very well.

Here's an experiment.

There is this black chip with the number "555" printed on it. It has 8 pins. A 1/2 circle is carved out of one end of it, or a carved in dot is created in it. Align the chip so that the marking you see is on the left. The pins are numbered 1 through 8 starting from the bottom left going to the bottom right, then from the top right to the top left. This chip is a "timer".

Now you will need two resistors. These are mini peanut-shaped items with stripes on them and metal wire coming out of their ends. This metal wire is more known as leads (not pencil lead). Look for the following stripe colours in order: brown, black, yellow, gold. you might have to move the resistor around to see it. This resistor has a value of 100 kiloohms.

Also, get a hold of a resistor that has these color of bands on it: orange, orange, black, gold. This resistor has a value of 330 ohms.

You will need an electrolytic capacitor. These are barrels with markings on them, and they have two leads as well.

You will also need wire, and a breadboard (an item that has many holes in it.

Plug the chip into the center of the breadboard. make sure that when the chip is seated into the sockets, you can read the 555 properly, not backwards.

In the following, when I say connect, it means insert the device in the same column the pin is in. It doesn't have to be in the same socket, as there are 4 other sockets to play with.

Connect pin 1 (of the chip) to the -ve (bigger round connector) of a 9 volt square battery. You will need a wire to do this.

Use a piece of wire to connect pin 2 to pin 6.

Connect the capacitor to pins 1 and 2. The leads of the capacitor cannot touch each other.

Connect the 100 kiloohm resistor to pins 6 and 7.
Connect the other 100 kiloohm resistor to pins 7 and 8.
Connect pin 8 to +ve.
Connect pin 3 to one lead of the 330 ohm resistor.
The other lead goes to the anode of an LED.
The cathode of the LED goes to the -ve of the battery.

The LED is a light-emitting diode, or in simple terms, a light bulb with better efficiency. The anode is the "positive" part of the LED, and the cathode is the "negative" part. When looking at a new LED, you see two plates of different sizes inside. The larger plate is connected to the cathode lead, and the smaller plate is connected to the anode lead.

You should see the light go on and off at a constant rate.

I might have gave too much for an answer, but Talking Electronics Interactive will be able to provide much more information for free.
They will have circuit diagrams, one of them which described my circuit, but instead used different values.

Basically, I showed you how to make what you need. As for the same casing, good luck.

 

[stevehawkes]

many thanks to your all.

Regarding the post that MSTECHCA posted

I read this with great interest, before I investigate further I need to be sure that the circuit you described will do

- flash both lights
-allow me to speed up / slow down the rate of flash
-allow me to alter the length of time the LED's are lit.

I reckon I am going to have to try and work out how to build a circuit that does this as the velleman kit I got, judging from the replies (thanks to you all) will not do what I want it to with a simple modification.

I am trying to create a beacon. Think of a light house light, that does not rotate and you'll be reasonably near.
2 / 3 second on and the same off is roughly how I would like the circuit to work.

I am sorry if it would have been helpful to you folks to have know that first

regards

Stephen