Cheap Square Wave Generator

[Magluvin]

Got the little square wave gen boards yesterday.  So far it has some issues with upper freq at very low duty cycle. But should do the job for the projects im planning.

$10
1hz to 150kz
Output mirrors input level 3v to 30v
1% to 100% duty

https://youtu.be/BcTDSGTNWMw

Mags

[gyula]

Hi Mags,

Thanks for introducing the square wave generator you bought. Would like to ask, when you have time to check the current draw (at say 50 kHz 50% duty and the output is not loaded) from say 12V and 24V. I guess it is in the 10 - 20 mA range or even less but this data is not included in the specifications anywhere I looked at.   

In the meantime I found the same module type with two and 3 outputs (channels as the sellers call them) too. This very likely means the 2 or 3 outputs will have the same frequency you set in as usual but the duty cycle can independently be varied per channels.  At least this is how I understand the ebay offers, see some here (all offers have free shipping and at least 4 week delivery time):

https://www.ebay.com/itm/173285815317   3 channel  US 3.49 

https://www.ebay.com/itm/332862159283   2 channel  US 3.85 and 3 channel US 4.70

https://www.ebay.com/itm/273107868051   1 channel GBP 1.88 LCD and 2 channel GBP 1.42 but with 7 segment LED display

Thanks,
Gyula

[Magluvin]

Hi Mags,

Thanks for introducing the square wave generator you bought. Would like to ask, when you have time to check the current draw (at say 50 kHz 50% duty and the output is not loaded) from say 12V and 24V. I guess it is in the 10 - 20 mA range or even less but this data is not included in the specifications anywhere I looked at.   

In the meantime I found the same module type with two and 3 outputs (channels as the sellers call them) too. This very likely means the 2 or 3 outputs will have the same frequency you set in as usual but the duty cycle can independently be varied per channels.  At least this is how I understand the ebay offers, see some here (all offers have free shipping and at least 4 week delivery time):

https://www.ebay.com/itm/173285815317   3 channel  US 3.49 

https://www.ebay.com/itm/332862159283   2 channel  US 3.85 and 3 channel US 4.70

https://www.ebay.com/itm/273107868051   1 channel GBP 1.88 LCD and 2 channel GBP 1.42 but with 7 segment LED display

Thanks,
Gyula

hey Gyula. No problem.

Ill do that input test. I suspect there is a regulating circuit, probably a resistor and zener to run the device at various voltages, so its possible the idle input will rise as the input voltage rises to 30v. Will see. Just fiddled yesterday. Was able to get my bifi to ring a sine at 12.7khz via 1 wire from the gen at 50% Duty. Rung up to near 7v.

Will be trying to drive a mosfet tonight to pulse the Orbon and see how it goes. Then I will wind Brads SS device and give that a go also if all goes well.

Mags

[Magluvin]

Idle currents...

5v    22.4ma
15v  27ma
30v  33.9ma.

not much more than a typical led. Of which the screen is backlit by a side led under the white plastic to the left of the screen.

Mags

[Verpies]

Can any of these generators do a 100ns pulse every 2s ?

[gyula]

Idle currents...

5v    22.4ma
15v  27ma
30v  33.9ma.

not much more than a typical led. Of which the screen is backlit by a side led under the white plastic to the left of the screen.

Mags

Hi Mags,

Okay, thanks.  In the meantime I found the PCB side photo of the module and it turns out there is a 1 kOhm resistor labeled as R1 (lower left corner) in the collector of transistor Q1 (upper left corner). This means the 1 KOhm gives an additional load (though not so much) for the supply voltage as Q1 is controlled by the output pulse. The output (labeled as PWM) is the common point of the collector and the 1 kOHm resistor.  So this makes up for the total consumption, in addition to what you said.

For verpies:  here is some review https://www.wanhunglo.com/2018/pwm-pulse-frequency-duty-cycle-adjustable-square-wave-signal-generator-module-whl-43  and the microcontroller is an ST 8S003F3P6

Gyula

[JimBoot]

mine are ordered. Will take a couple of weeks to get them.

[Verpies]

I read it and it cannot do 100ns pulse every 2s.
I think it could with a better firmware...

[Magluvin]

I read it and it cannot do 100ns pulse every 2s.
I think it could with a better firmware...

Hey Verpies

Its not the greatest. But for some projects and experimentation I find it very useful.  There may be times where we need more than 1 or 2 or 5 gens. Could get expensive otherwise.  And, it is so inexpensive that a budget minded experimenter can afford this and do many things with it. 

Mags

[JimBoot]

Mine just arrived. Have the alnico mag experiment hooked up so I'll be trying that. How are yours doing Mags?

[PhysicsProf]

Mine just arrived. Have the alnico mag experiment hooked up so I'll be trying that. How are yours doing Mags?

In what thread is the alnico mag experiment discussed?
Also, how is it going?
Thanks!

[Aking.21]

Hey Verpies

Its not the greatest. But for some projects and experimentation I find it very useful.  There may be times where we need more than 1 or 2 or 5 gens. Could get expensive otherwise.  And, it is so inexpensive that a budget minded experimenter can afford this and do many things with it. 

Mags

By coincidence I have just received half a dozen of these.  My advice is to use a gate driver for a sharper pulse ie a disruptive discharge(Tesla) .  This is something I have learnt fom Rick Friedrich and it will give a much higher voltage output especially at resonance although the gate driver will consume more current. It will only work with a series tank circuit although you can use it with a parallel tank if you put a small  cap in series.

[Magluvin]

By coincidence I have just received half a dozen of these.  My advice is to use a gate driver for a sharper pulse ie a disruptive discharge(Tesla) .  This is something I have learnt fom Rick Friedrich and it will give a much higher voltage output especially at resonance although the gate driver will consume more current. It will only work with a series tank circuit although you can use it with a parallel tank if you put a small  cap in series.

Thanks.   Sorry.  Havnt had a lot of time. Workin 12 or more hours a day the past month. Just finishing touches to go from here and then I can take a break.

Mags

[Magluvin]

By coincidence I have just received half a dozen of these.  My advice is to use a gate driver for a sharper pulse ie a disruptive discharge(Tesla) .  This is something I have learnt fom Rick Friedrich and it will give a much higher voltage output especially at resonance although the gate driver will consume more current. It will only work with a series tank circuit although you can use it with a parallel tank if you put a small  cap in series.

Wanted to look into drivers. Probably make one. Do you have a circuit in mind?

Mags

[partzman]

Thanks.   Sorry.  Havnt had a lot of time. Workin 12 or more hours a day the past month. Just finishing touches to go from here and then I can take a break.

Mags

Nice work!  Just curious, fleece and mdf or....?

Regards,
Pm

[Magluvin]

Nice work!  Just curious, fleece and mdf or....?

Regards,
Pm

Hey Pm

I have been using pvc board for some years now instead of wood.. Its lighter. not really any dust when cutting. Heat and bend. Waterproof. Superglue is your best friend. And fiberglass loves it also.
I use Tshirt material for shape, apply resin and cure to give a surface for fiberglass. I use 10oz cloth glass. Less mess. Goes around rounded edges and molds into small areas with minimal sanding back to the original shape. Just do 1 layer of glass at a time to avoid shrinkage which can mess up the shape of the framework. I also prefer layup resin instead of cheaper resins as it has minimal shrinkage.  And the cloth, applied 1 layer at a time, you simply trim excess after cure with a razor knife.  I only use mat glass for heavy layup of some things like sub box bottoms that fit shapes in the vehicle where shrinkage doesnt occur much.

Lots of guys down here us the fleece or sweat shirt material which takes on a lot of resin(can cause lots of shrink issues unless you use brackets and screws to hold things in place), then they just apply bondo/filler and call it fiberglass. Mags dont play. 

Mags

[Magluvin]

Apply 1 layer od 10oz cloth to each side of 3/4 pvc and it is stiffer and lighter than any wood out there.

Mags

[partzman]

Hey Mags,

Thanks for the info and the in-process pix.   I've never used PVC foam board before even though I've done quite a bit of composite stuff so I'll give it a try on my last project, a '61 Corvette resto-mod.

Regards,
Pm

[Aking.21]

Wanted to look into drivers. Probably make one. Do you have a circuit in mind?

Mags

No I am new to it. Rick put me onto them so it's a learning curve Im afraid. There seem to be several micro chips around- so I guess it's trial and error. The purpose is to get a straighter sharper spike and generate more impulse power - both electrical and magnetic.  But you have to match up or something will blow.

[muDped]

Here's a link to Mouser Electronics listing a couple of
MosFet Gate Driver chips.

Be sure to download the Data Sheets for any chips which
may be of interest.  Getting to know the characteristics
and ratings of the chips is essential to assuring their
suitability for the application in mind.  The Data Sheets
often have example circuits which are very helpful.

The Data Sheet for the UCC27524 chip is especially
good in that it contains a detailed description of how the
Gate Driver circuit operates.

The gate driver circuits may be paralleled if desired for
increased output current capability.

Low Side Driver Chips are less complex and inexpensive.

High Side Driver Chips are more complex and cost more.

[Magluvin]

Was looking into this with 555 timers. 555 is basically a comparator circuit.  Will try it to see if it sharpens up the square wave.

Mags