epemag

[radium98]

ANy of the the forum members , have experience with the project of epemag EPE magazine ?

[Albert H]

Which project?

[radium98]

Vupeak meter the lcd does not start.

[Albert H]

Can you scan the article so we can see it here?

My favourite VU / PPM uses LEDs. It's a really simple circuit, you can adjust the step sizes and the number of steps. My original one uses LM339 quad comparators, and a LM3900 Norton op-amp for the rectifiers. It's reasonably easy to get it set accurately, and to get a BBC-style PPM characteristic. I have switchable modes of operation, allowing the display of both channels indepedantly or M and S components.

I've recently been experimenting with processing the sum and difference signal separately, to see if there's any advantage to be had. The M & S display has been very useful.

[radium98]

LCD UV Meter.rar

Albert .Yes i have the magazine issue , and and saw many on the web has done it succesfully , and i want to make it a digital way to put at th my banch , it use a pic 16f88 , i dont need any led .and the magazine is in the UK .So some hand to see what is wrong at my end , if you want to help me .
someone done it .

and mine pcb .NB i have debugged everthing regarding to schematic , voltage .connections and tracks.
Thanks for help.

[radionortheast]

I could only manage the one transistor fm microphone, in epe or electronics world though I loaded it up with 2n2219 transistor, was the first time I recieved a signal in some woods about 1 mile away, weak but there. When I had to change the frequency it wouldn’t work, veronica came along (I don’t know when adverts started appearing) I soldered up the 1w stereo, took all day never expected it to work at all never heard anything like it, I got a fully quieting signal at the same place, I went through every kiss in ibiza, gatecrasher, essential selection cd, it was the most fascinating thing. I suppose nothing can help you here, I was only looking through these magazines the other day through the world radio history archive, trying to find adverts https://www.worldradiohistory.com/UK/Wireless-World/ .
I don't think i'd want to atemp many of the projects even now lol, there are a very useful circuits, in one of the magazines they would get obsessed by distortion in audio amplifiers, how to measure it, can imagine them parading around in a pair thd tights, lol the whole thing became about thd, you'd think give it a rest. best left to hannah fry or wenesday addams or I don't know who else would do that

[Albert H]

That's a horrible circuit! Using a 555 to generate a negative supply rail is OK, but noisy, and their less than perfect design gives an asymmetical supply : +12V and -9V. The rectifiers will be less than accurate - you need a properly symmetrical supply for real accuracy.

I'd use a modern switched-mode supply inverter IC (ICL7660 or similar) which gives a symmetrical output, and much less noise than the awful way it's done in this circuit.

The A to D converters in the PICs are less than perfect though probably OK for a crude, approximate display like this.

I prefer an LED display - much easier to read than an LCD, and it's really easy to add add "Over" indicators to show rapid transients. The circuit I use can be built for various step sizes, and practical radio studio use shows that LED bargraphs - usually 16 steps - with green LEDs at first, up to 0dB (PPM 4), then yellow or amber LEDs up to +8dB (PPM 6), with high intensity red LEDs for over peak level up to +12 dB (PPM 7). It the top end of the chain, I'd have Peak transient indicators, also HE Red, which give a pulse-stretched indication of fast transients.

To be honest, it's hard to beat the traditional BBC PPM for simplicity and ease of use. Unfortunately, the Ernest Turner meter movements with the correct ballistic and white numbering and scale markings on a black background (displaying 0 to 7) are horribly expensive these days, but are hard to beat for accuracy and ease of use. It's easy to teach even the thickest of DJs to read a PPM!

On my studio mixer, I have three twin-needle PPMs: Left and Right outputs with red and green needles on the first one, a M and S (stereo sum and difference) meter with white (M) and yellow (S) needles, and a third one (also left and right) for pre-fade levels. They provide very clear and easy-to-use indication.

Recently, I've been trying to get hold of some of the Ernest Turner projection meters, so I can shine a larger display onto the wall behind the desk (more as a curiosity, rather than for serious metering use!).

[radium98]

My problem, is it is not working with me . the display wich is working , is from a pcb from someone else from the net , i wich i can make it work with some help .the pic does not been properly configured with me , And as the project is a bit old , i ask if someone still have the proper hex around .Otherwise i have a freind who will pass there , maybe he will buy than a programmed one , if it is not solved here .
regards.