Junctec? - Page 1
Forum section: electronics / projects

author: Terry Bites
author_rank: Super Contributor
timestamp: August 26, 2025, 11:54:14 am
content: I'm not one to talk up cheap gear but....I borrowed a Junctec signal generator to play with.A JDS8060 8080 Dual Channel Function Generator 14bits 80MHzIts just under £120 on Ali. It feels so light you think it must be crap but its surprisingly good for the price.I checked it on my recently cal'd Racal Dana counter (still in love) and its not far off after 20min of warmup. I left it on overnight and it was still on frequency.Maybe I got lucky. So not so Junk. I hate the lack of numeric key pad entry but you get what you pay for here. No external ref input sadly.I think it wouldn't be too hard to modify that though. Must do a teardown. BTW, what's the best way to make an external ref automatically override the internal?Its dual chanel and has all the usual waveforms, modulation types, arb, exteral mod input, burst (on external sync) DC offset, CV input etc.You can even use one channel as a counter while the other output is a generator. Stores user presets. Thats great for low cost bench.It can be mains or 5V adaptor powered. That might be handy if you want a floating source to drive balanced lines.Remote control via PC, IOS or Andoid app. TTL GPIOs and I think RS232 coms too.For a beginner on a budget I'd recomend it.https://video.aliexpress-media.com/play/u/ae_sg_item/2209337394332/p/1/e/6/t/10301/1100067032873.mp4?from=firefox

author: mawyatt
author_rank: Super Contributor
timestamp: August 26, 2025, 01:23:29 pm
content: Quote from: Terry Bites on August 26, 2025, 11:54:14 amRecall someone utilized injection locking the Internal 10MHz Oscillator which effectively switched to the External Reference when available on one of the low cost AWGs. Inserting a small resistor or inductor in the Ground or VCC line and injecting the Ext Ref by means of a series RC into 10MHz oscillator might do the trick!! This couples the Ext Ref into the Internal Oscillator which "locks" to the external signal when the external signal is very close in frequency. The Ext Ref signal level as "seen" by the Internal Oscillator doesn't need to be large, just a few 10s of mv.When no External Ref is present the 10MHz Oscillator determines the Internal Reference, when an External Ref is present then the Internal Reference becomes "Disciplined" by the Ext Ref.Best

author: Terry Bites
author_rank: Super Contributor
timestamp: September 06, 2025, 03:58:28 pm
content: Its a bugger because its ref osc is 50MHz.I'll have to upscale and thats put me off messing with this thing.I recently discovered that it has a lot of amplitude jitter at the top end.I found the perfect ic for a 10MHz clock switch over. I think this might just work, I'd get 4x50R ref outputs too.Cheap enough for a quick lash up. Simulates just fine.

author: mawyatt
author_rank: Super Contributor
timestamp: September 06, 2025, 04:15:39 pm
content: It still might work with the 50MHz oscillator. We recently posted an article on EDN about Injection Locking Divider here:https://www.edn.com/injection-locking-acts-as-a-frequency-divider-and-improves-oscillator-performance/This might also work as a Multiplier altho we haven't tried, and since the 50MHz is the 5th harmonic of 10MHz this just might lock on!!Worth a try anywayBest

author: BennoG
author_rank: Frequent Contributor
timestamp: September 06, 2025, 05:54:30 pm
content: I have the 80Mhz and the older 20Mhz. I love both of them.You can do channel coupling in ways I have never seen on generators.I used it once to generate a AB encoder signal that hat a sweep on the speed and worked like a charm (they were rock solid on a 90 degree angle, regarding the sweep)

author: Terry Bites
author_rank: Super Contributor
timestamp: September 08, 2025, 04:52:42 pm
content: Ive seen this before but it doesnt say how to control the division ratio.It just says you can. It doesnt say at what point in the circuit the external signal is applied either.Any how, I wanted to go in the other direction. The 501 from Renasas seems to be an economical solution.Its accademic. I'm intersted in acquiring something with more grunt. I'll give it back to the owner...

author: mawyatt
author_rank: Super Contributor
timestamp: September 08, 2025, 05:21:25 pm
content: The 5th harmonic of the 10MHz external ref would allow the AWG internal 50MHz oscillator to lock-on if the ext ref frequency is close enough to 10MHz (like within <100ppm). You can try coupling to 50MHz oscillator Ground, Output or VCC pin at first without any changes to the 50MHz oscillator, try a series ~470pF and ~100Ω for coupling from the ext ref for starters. If this doesn't work you may need to create a reasonable impedance (2~5Ωs) in the Ground or VCC line to the 50MHz oscillator to "work" into from the ext reference.The nice thing about this approach, besides simple, is the AWG 50MHz oscillator produces a 5X phase/frequency locked replica when the 10MHz ext ref is connected, and the oscillator free runs when the ext ref is not present.Best